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What exactly was so broken about Urza's Block?
I've often heard it said that the Urza Block (Urza's Saga, Urza's Journey, Urza's Destiny) was the most powerful, broken block in Magic history, with decks able to win on turn 1 or 2. I also saw it stated (in some MaRo article) that something like 20 cards were eventually banned from that standard format in an attempt to restore balance. However, I've never seen a good, detailed explanation of what, exactly, went wrong, which cards were to blame, and how the uber-powerful decks of that era actually worked. Can anybody here offer an explanation or a link to an external source?

Preface: I've been drafting this for a few days now. I focused on the cards that were banned, because those were the most broken. I'm sure there were dozens of other combos not included here, and this is by no means giving the fullest extent of how the cards could be used to maximize their broken-ness.
The first step is to take a look at what cards were available at the time. Mirage had just rotated out, which leaves us with the Tempest block and of course Urza's block. This leaves us with some very powerful 0 and 1 mana artifacts: Lotus Petal, Mox Diamond, Ornithopter, and to a lesser extent, Spellbook.
Note that with Lotus Petal and Mox Diamond, you have yourself 2 mana available on your first turn without playing a land. (To be fair, both of those are part of Mirage, not Urza's.)Those mana can go into a Grim Monolith, which in turn gives you 3 mana when tapped. Make your land drop a Tolarian Academy and suddenly you have 6 mana available on your first turn, and you only needed four cards to do it. I think we can agree that 6 mana on the first turn is broken in an innumerable number of ways. This led the Academy to be the first to be banned.
Along with the Academy was Windfall. This was broken for a couple of reasons. First, consider a card like Divination, which has a card advantage of 1 for 3 mana at sorcery speed. (You draw two cards, but you had to spend 1 card to do it). When you also consider Azure Mage it becomes clear that in blue, 3 or 4 mana is appropriate for 1 in-hand card advantage. Now, consider how fast you blow through cards here: you dropped four cards (lotus, mox, grim, and academy) as well as any other 0 drop artifacts, and use a Windfall. You discard your 0 or 1 non-playable cards and pick up 7 more. Your opponent dumps all 7 of his and draws 7 more. You just gained 6 or 7 card advantage for 3 mana. That just isn't competitive.
The other aspect of Windfall is that your opponent is also playing combo. It was not uncommon for people to mull down to 4 to get their combo. While this will lower the card advantage you get from Windfall, it essentially wastes your opponent's mull! He now has to settle for whatever 4 or 5 crap cards are on the top of his deck. If you went first, then your opponent has not had an opportunity to play, but now is facing you with at least 6 cards on the battlefield, the ability to generate 6 or more mana a turn, and to top it all off, you just gave him a complete crap hand instead of the one he mulled to get. Bummer. So understandably, those were the first two to get banned.
In the next round of bans, you see Dream Halls get the axe. Now, without Academy and Windfall to pump up your early mana, this isn't as effective. It was costed such that you can't use it until turn 5, and you have to use two cards to do it instead of one. So since they were expecting you'd use this on turn 4 or 5, it would end up being very damaging. And under normal circumstances, it is. But there's one small problem. You discard that other card instead of paying the cost. This is supposed to make it so you can't use it. But Yawgmoth's Will made it so you could use it. If you Dream Halled two cards, you could cast the other two cards with Yawgmoth's Will. And with all the mana you have and card draw available, it's reasonable to pull this off.
Another one that was banned was Earthcraft. This card used to look like this:

Creatures you control have: T: untap a target basic land.

However, it was decided that splicing text onto cards was a bad thing. So it was changed to

Tap an untapped creature you control: untap a target basic land.

in the name of being easier to work with. Unfortunately, it had the side effect of making creatures with summoning sickness able to tap for mana, which is decidedly overpowered.
Fluctuator was banned because there's about 40ish legal cards with cycling, and they're all (Cycling 2). So they all basically let you loot them for free to burn through your deck. Cycling for free is broken. This combo didn't take much to come together.
Lotus Petal was banned for the combo listed out above, and I'm sure there were dozens of variants of it.
Recurring Nightmare was banned because three mana and a creature (Probably 0 mana) was too little to return a creature from the graveyard to the battlefield, considering it goes back to your hand, not the graveyard (even if Yawgmoth's Will is active). It's even worse when the cards coming back are Great Whale, which yields infinite mana (although the infinite mana combo requires four lands on the board, and most games didn't last even that long!)
Time Spiral was the last of the second round to be banned from standard. It had the same problem windfall did, where you got to draw seven cards (including spells you've already played! How convenient!) and get the massive card advantage. Now this is 6 mana, not 3, and we know there's a gigantic difference between 3 and 6 (way way way more than twice as much). But as we've established, you can get 6 mana on your first turn... And to top it all off, you get to untap 6 lands. Umm, yes that's just a little too powerful.
The next big card to get the axe is Mind over Matter. This is simple: you discard (which we've established there's already massive card advantage here, which lessens the penalty...) and you get to untap an artifact (with academy, mana, or the mana artifacts themselves), creature (with earthcraft, mana, or Birds of Paradise), or land (mana). So you get even bigger mana amounts.
Memory Jar was so broken it was the only card to get an emergency ban. Basically you get to draw and play with 7 cards. As we've established your hand empties faster than a AK with a 14 round clip, you're going to get most of those cards out the turn you play it. And since 5 mana isn't all that much to get on turn 1, you might end up with this on turn 1, which when combined with another draw combo will give you access to 20 or more cards on turn 1. Broken? Yep. Unlike windfall, this doesn't kopper your opponents starting hand, as he'll get it back at the end of the turn. But you'll have another 4 or 5 permanents on the board, so what's he really going to do to you at this point anyway?
Like I said, these probably have even better ways to get the most out of them. But hopefully this gives an idea of exactly how these things were broken, and why Wizards reacted the way they did with all the bans. For what it's worth, this is the first genuine test of Wizards reacting to the fan base, and I would go so far as to say their biggest mistake up until that point and even to this day (needless to say they learned many lessons from it!)
Edit to add: I take it back. Their biggest mistake to this day is the reserved list, and I'm happy to die on that hill. <3

I think many would say that Affinity and artifact lands eclipsed this, and were there biggest mistake to date.

Mirrodin was another broken block, for sure. But for the most part you had to build your deck around a select card or two's brokenness. With Urza's block, you had a number of immensely powerful cards that could slide into any number of decks to make them broken. The only thing that might make Mirrodin's sins worse than Urzas' is the notion that after ten years of making cards, you'd've expected less brokenness.

This is exactly the kind of answer I was hoping to see! +1

Free (or nearly so) mana, cards, creatures, spells, etc. are almost always the source of brokenness. This answer illustrates that very well.

It's also worth noting that there were other cheap power cards like Dark Ritual and Vampiric Tutor that were underestimated at the time. In some cases the banned cards just turned out to be the best things to do with the real broken cards; history has shown that Mind over Matter isn't that bad when you don't have a Tolarian Academy to untap with it.

Earthcraft's banning was less about the summoning-sickness issues and more about specific infinite combos with Fertile Ground/Horseshoe Crab and Recurring Nightmare/Workhorse/Overgrowth, which - as convoluted as it sounds - was much more consistent in the underpowered environment of the time, especially stapled into a 'standard' Recurring Nightmare/Survival of the Fittest engine.  Earthcraft was deemed (justifiably!) an enabler and got tarred with the same brush.

The executive summary to the question "what went wrong in Urza block?" is: WOTC believed that people really like combo, so they made a block of  combo enablers. It went as corsiKa described.

I played during combo winter.  Some of the responses are good, but a couple issues.  For example, when Urza's Saga was printed, 5th Edition was the Standard core set.  So no one ran Grim Monolith; it was too expensive.  Everybody used Mana Vault (it was printed in 5th).  So a typical Academy build would look something like this:
4 Ancient Tomb
4 City of Brass
3 City of Traitors
4 Tolarian Academy
4 Wasteland
4 Lotus Petal
4 Mana Vault
4 Mox Diamond
2 Scroll Rack
4 Voltaic Key
2 Urza's Bauble
3 Mind Over Matter
3 Intuition
3 Power Sink
4 Stroke of Genius
4 Time Spiral
4 Windfall
And it was banned because it was annoying.  The games would look something like this:
Game 1
Your Turn 1: Tolarian Academy, Mox Diamond (pitch City of Brass), tap Mana Vault to play Voltaic Key, use Voltaic Key to make a total of four colorless, tap Tolarian Academy to Time Spiral, reshuffle hand, deck, and yard, then draw seven and untap Tolarian Academy.  Play a few more artifacts, tap Tolarian Acadamey to play Mind Over Matter.  Discard a card to untap Tolarian Academy, then tap it for however many artifacts you have (probaby six or seven). So, at this point, Mind Over Matter basically reads: "Discard a card: add a U to your mana pool for each  artifact you control."  After chucking a couple of cards to the MOM to make a bunch of mana with Academy, you cast Stroke of Genius targeting yourself and grabbing a chunk you your library (maybe 15-18 cards).  Repeat the process, then Stroke of Genius yourself for the rest of your library.  Play every artifact in the deck.  MOM now nets about 17 blue mana with each discard, and you have about thirty-five spare cards to chuck.  So you make a metric butt-ton of mana, then target me with 140-point Stroke of Genius.  Game over.
Game 2:
My Turn 1: ["YAY!  I get to play a land this game!!!"] Mountain.  Go.
Your Turn 1: Tolarian Academy, Lotus Petal, Mox Diamond, Mana Vault, Time Spiral...(see game 1 for the rest).
And if you think this is ugly, google Zvi Bargain.  Without a doubt the most broken standard deck that ever existed.
Edit: Combo Winter Continued...
Along with the infamous Academy deck, another blue goey-offey deck was High Tide.  Much like the Legacy High Tide of today, this one used High Tide, Mind Over Matter (Candelabra was not extended legal, and nobody played type 1.5, which is what was legacy was called back then).  However, unlike the fast High Tide of today, back then High Tide was basically a draw-go deck that finished with a combo.  The goal was to go off as late as possible; turn 15 or 20 if you could wait that long.  I liked the control aspect of High Tide, and I actually played High Tide over Academy.  But, like a draw-go, you still had to find the right balance so you didn't flood, but had the mana to fight a counter battle if need be.  Plus, the deck got absolutely crushed by Steel Pox (another really fun deck of the era that gets overshadowed by the combo decks of the day).
So High Tide was a strong deck, but not necessarily broken.  There were a couple of noteworthy innovations with the deck.  For example, one such innovation (I believe the brain-child of Johnny Magic himself) was to run Thawing Glaciers to smooth out the mana base.  It also allowed for the use of Brainstorm which, until that point, was considered useless.  Also, since it doesn't return to the hand until end-step, pairing Thawing Glaciers with Mind Over Matter allows you to dig every island out of the deck on the turn you go off.  The player would activate Thawing Glaciers, untap it with Mind Over Matter, activate it again, etc...  Then untap all eighteen or so islands with a Turnabout - it was pretty cool!  Even so, the deck still needed the right balance, and needed the right spells for the metagame.  But when Dream Halls was added to the mix, the deck no longer punished players for bad deck design. Handful of counters and no mana to cast them?  No problem!  Discard Force Spike, cast Force of Will.  Handful of Garbage?  No problem!  Discard Force Spike to cast Turnabout at your opponent's end-step, then Arcane Denial your own Turnabout and grab four cards next turn.  With Dream Halls, any idiot could pilot a High Tide deck to a top eight finish, so it had to go.
But some cards during this period were banned out of pure paranoia - Fluctuator for example.  There was a proposed Fluctator archtype which consisted of 4 Fluctuator, 1 Lotus Petal, 1 Dark Ritual, 1 Haunting Misery, and a bunch of cycling cards.  A player would (in theory) resolve Fluctuator, cycle through their library, pop Lotus Petal, cast Dark Ritual, cast Haunting Misery, then exile the 20 cycling creatures for the win.  In reality, the deck was unworkable.  The cycling lands came into play tapped, it was vulnerable to any kind of disruption, there was no real sideboard, and you couldn't Mulligan.  Doing so may cause you run out of cycling cards before you hit the requisite number of creatures in the yard.  Deck beat itself most of the time.  Another one of these paranoia banning was (in my humble opinion) Memory Jar.
Now, a case can be made against Memory Jar.  Randy Buehler and Eric Lauer piloted identical Jar Decks to top eight finishes at GP Vienna in 1999.  But they were both beat out by Kai Budde's High Tide, and a Counter Sliver deck, so it was beatable.  And it was prone to fizzle, and hard to pilot.  In fact, a friend of mine (a guy named Mark Gordon) won GP Kansas with a Lackey Sligh deck.  Despite being legal, there wasn't a single Memory Jar deck in the top eight of that event.  So, while many will disagree, I think the Jar banning was more attributed to paranoia than actual format-breaking.  Plus, people were sick-to-death of combo decks.
Later, I'll do another edit and cover all the Bargain abuses.  Yawgmoth's Bargain was format-breaking!!!
Edit 2:
By this time, it was mid-1999, and things seemed to be straightening out.  Anything with nasty combo potential was banned (or about to be), and Magic was getting back to normal.  One of the more popular Standard decks (at least in my hometown) was a deck built around Living Death and the 187 creatures from Urza's Legacy.  Wildfire was another popular choice, as was mono-green and mono-red aggro decks.  It seemed as though the ugly combo winter had passed, and spring and summer seemed to bring vibrant, interactive decks back to the game.
Then Urza's Destiny happened...
The set contained a card which some of the ugliest combo decks to-date were built around: Yawgmoth's Bargain.  It was disgustingly broken!!!  And there were many decks built around it.  One variant would use Flash to put an Academy Rector into play, not pay the reduced cost, then exile it to fish out Yawgmoth's Bargain.  Another variant (and my personal favorite) used Intuition to search for a Yawgmoth's Bargain, a Delusions of Mediocrity, and a Seismic Assault.  Then it used Frantic Search to pitch whichever one was sent to the hand, then cast Replenish, draw about 25 cards, and dump lands to Seismic Assault for the win.  But the worst variant was the type that Zvi Mowshowitz piloted to a top eight finish at Nationals.  I'm not going to post the decklist, but you can read about it here: http://www.starcitygames.com/magic/fundamentals/8452_Degree-of-Difficulty.html
On the Standard side, the problem with the deck wasn't necessarily the power level (although the power level was absurd).  The problem was that playing against it was akin to a slow, agonizing death - it was sheer torture!!!  The opponent would resolve a fast Yawgmoth's Bargain (usually turn two or three), draw cards one-at-a-time, and periodically pause for several minutes at a time in order to perform a bunch of mental gymnastics to calculate how to play out the hand to get more cards, play a few cards, draw a few more, pause and think for another five minutes, play some more.  Eventually with untap shenanigans like Turnabout and Voltaic Key, they'll have generated enough mana to resolve a lethal Blaze.  A typical game went something like this:
On opponent's first turn, they play Underground River and Mox Diamond, then pass the turn.  You play a land and say, "go."  Then, at your discard phase, they cast Vampiric Tutor.  Then they slowly scan through every card in their library, then scan through it again.  Then they stop at a card, scrutinize it, look at their hand, look at the card, look at their hand again, look at the card again, think for a minute, decide not to take it and repeat this process until they find a card that will work.  Then, on their turn, they play City of Traitors, tap it for Grim Monolith, tap Grim Monolith for Voltaic Key, tap Voltaic Key to untap the Grim Monolith, tap Grim Monolith for a total of four colorless mana, cast Dark Ritual off the Mox Diamond, then cast Yawgmoth's Bargin with one black floating and an untapped Underground River.  Then they start drawing cards one-at-a-time, announcing their new life total before each draw...
"Seventeen" (draw a card)... "Sixteen" (draw a card)... "Fifteen" (draw a card)... "Fourteen" (draw a card)...  Then they would stop and do arithmetic in their head for a full five minutes.
"Thirteen" (draw a card)... "Twelve" (draw a card)...
Then they pause for another five minutes to do more mental calculations.  Meanwhile, you have nothing to do but stare at their forehead and watch them crunch numbers.
"Eleven" (draw a card)...
Then you shout, "Oh, FOR F**K'S SAKE!!!  LET ME KNOW IF YOU WIN."  Then you put your hand down, walked away from the table, got a Coke, smoked a cigarette, then returned fifteen minutes later, and they were still trying to go off!  No exaggeration; this is what playing against Zvi Bargain was like.  And people HATED it!!!
It nearly ruined the game.  Players were quitting in troves.  It was like the stock market crash that precipitated the Great Depression - so many people quit to play Ultima Online and liquidated their collections that the singles market was saturated, and card prices plummeted as a result.  At the time, I actually bought a white-bordered Mox Jet for sixty bucks.  It was bad.  It was really bad.  Magic barely survived.
Fortunately, the rotation of Tempest block out of Standard deprived these decks of the mana acceleration that they needed to be busted.  The version of Bargain that existed after Tempest Block rotation (Sabre Bargain) was much more modest and fair.  Also, Masques Block brought in cards like Rishadan Port, Dust Bowl, and Tangle Wire that put these decks in check.
But, on the Extended side, Yawgmoth's Bargain was definitely broken based on power level.  Imagine Zvi Mawshowitz's version, except with Mana Vault instead of Grim Monolith, Cadaverous Bloom instead of Skirge Familiar (which was also an enchantment, so it could be cheated out like Bargain), Illusions of Grandeur instead of Delusions of Mediocrity, drain life was in, and Lotus Petal was still legal.  With decks like Academy before it, and decks like Flashhulk after it, turn one kills (or even turn 0 kills) were possible, but very rare.  This was not the case with Extended Bargin.  It won on turn one something like 30 or 40 percent of the time, and it won on turn two something like 60 or 70 percent of the time.  More often than not, you had to tutor for some element of the combo that you were missing, but about a third of the time, the opening draw had the cards to win the game on the first turn.  It you couldn't win by turn two, you should have Mulliganed.  It was by far the most broken deck that has ever existed!!!
At the time, Magic was in Standard season, and the banhammer came down quickly on Yawgmoth's Bargain in Extended, so it never saw major tournament play.  But not before the deck saw one major innovation.  Since the Illusions of Grandeur cost its controller 20 life when it left play, the whole nutroll of generating enough mana to resolve a big drain life became superfluous.  A player could simply Donate an Illusions of Grandeur and let the opponent die when they couldn't pay the upkeep.  While Yawgmoth's Bargain was legal, this process could all be done in a single turn.  When Bargain was banned, players substituted Necropotence for Yawgmoth's Bargain and spread the combo out over a few turns.  This evolved into what was probably the last broken combo deck of the series: Trix.
I don't know why, but at the time combo players had this weird fascination with naming combo decks after breakfast cereals (Fruity Pebbles, Cocoa Pebbles, Trix, etc.), so this is how Trix got its name.  Anyway, Trix dominated the tournament scene for a while.  In an attemp to slow the deck down, Dark Ritual and Mana Vault were banned in extended.  The ban didn't work, so they FINALLY killed it once-and-for-all by banning Necropotence and Demonic Consultation.  And this was the final nail in the coffin for the long series of crazy combo decks.
And this is the unabridged history of Combo Winter.

I created an account in this website just to comment this: I laughed so hard @  ["YAY! I get to play a land this game!!!"] Mountain. Go.
So hard I literally cried. Been years since I last laughed this hard.
Thank you! For the through explanation and for the laughs.

There have been several times in MtG history that the game was broken for a while. Black Summer, with the proliferation of Necropotence decks, Affinity decks that abused cheap artifacts and artifact lands, and Combo Winter that resulted in the largest number of bannings. Mark Rosewater discusses why cards get banned and restricted. While not all the cards are from Urza block, about half are, and Mark includes some interesting information about the prototype versions of some of the cards and why they are broken.

Lotus Petal (banned in Extended, restricted in Vintage) – This card shows how crazy Black Lotus is. During Tempest design, I thought it would be flavorful to make new “fixed” Black Lotus. Since I liked the idea of a 0 cost artifact, I lowered the number of mana it produced. The development team even questioned if it was too weak. In the end though we felt like the card might find some use in a very niche deck. I guess the niche decks were degenerate decks.

A timeline of DCI banning/restrictions is available if you just want to know the timing of the various bannings. This article has some nice background on Combo Winter, some examples of Pro Tour decks, and links to tournament reports of what decks were being played at the time. It has an interesting piece from Randy Buehler on why Memory Jar was emergency banned, the first and only card to be banned before its release. If memory serves, Wizards even offered replacement packs if you opened a Memory Jar, because it was unplayable.

“The one card that was ever subject to an emergency ban was Memory Jar, which has the unfortunate text “draw seven cards” on it. However, the power of Memory Jar itself isn’t why the DCI broke with its normal policy of quarterly changes. The only reason the DCI chose not to wait until the next regularly scheduled dates was because the very health of the Magic game was being threatened by “Combo Winter.” Urza’s Saga was four months old when Memory Jar came out in Urza’s Legacy. During those four months, there was a large and loud public outcry about the way the game was being ruined by all the “broken” cards in Saga. Since Saga was affecting all Constructed formats, not just Extended, there wasn’t anywhere for Magic players who didn’t like combos to go. They either played against a steady stream of combo decks, or they didn’t play at all. The DCI’s first round of bannings in December 1998 didn’t fix things and players began leaving the game in droves. It was vitally important to the health of the game to clean things up before too many more players walked away, so quite a large number of cards were included in the DCI’s March 1, 1999 announcement, which would become effective April 1 of that year. Players were optimistic that Combo Winter was finally going to end.

This is interesting, but doesn't ever answer the question. It doesn't explain what specifically caused Combo Winter, in terms of broken cards and combinations in Urza's block.

@SevenSidedDie, yor probably right. More could be said about what broken means. Buehler's comment hint that during Combo Winter the only viable decks were combo decks. Like with Affinity after it, the decks warped the format. You eith played combo, or played decks specifically to beat combo. It probably isn't enogh to mention that most combo decks play cards with a mana generating engine, card drawing engine,etc. I will have to list why each card is broken and how/which decks used it.

That would be great. An explanation of Affinity brokenness would have to at least mention the artefact lands, the Disciple, and maybe the Arcbound Ravager, or go further and explain their interactions and their enabling context. I was hoping for details like that since I too have heard about Urza's and wondered exactly what was wrong. I know why it was bad for the game, and how R&D messed up and learned a lesson, but not what it actually looked like in cards and combos.

I realize I'm a year and change too late, but for anyone who stumbles across this post, just run a few games with the following list and you'll get it:

3 Dream Halls
4 Mind Over Matter
4 Grim Monolith
3 Thran Dynamo
4 Voltaic Key
4 Lotus Petal
3 Mox Diamond
4 Windfall
3 Turnabout
4 Tolarian Academy
12 Island
4 Memory Jar
4 Time Spiral
4 Stroke of Genius

Your sideboard would essentially be:

X Phyrexian Colossus
X Masticore
X Phyrexian Processor
X Morphling

As alternate win conditions.

X Counterspell
X Quash
X Dismiss
X Defense Grid

For the Stroke mirror and the counters of any Counter-Phoenix or Counter-Slivers or Counter-Troll or Counter-whatever.

X Hibernation
X Evacuation

For the Gaea's Cradle decks. Nobody else had a chance of racing you, so nobody else deserved sideboard slots.
As for the main deck, there were, of course, variations. Maindeck Masticores and shaving numbers on Thran Dynamo and the enchantments to include Evacuation or Counterspell was common, but generally a bad idea. With a deck like this, you should be all-in. I experimented with a list that played Skyshroud Forest for Crop Rotation. If you didn't find Mind Over Matter yet, you could sacrifice an Academy to go get another Academy. I was super pissed when they banned Memory Jar because I had just spent all my money on a pre-order playset at age 10 as soon as the card was spoiled in Scrye or The Duelist or whatever magazine. Then they proceeded to ban the whole deck and all the trading and buying I had done for the past year.

You're not really answering the question as it was asked. Why were certain cards or combinations of cards game breaking?

@bengoesboom I think the answer is trying to show rather than explain. It can be difficult to explain why something is busted, but it becomes apparent the moment you see it in action. The first time I looked at a storm list I didn't get it. Then I played it. I got it lol.

Tolarian academy, Yawgmoths Will, Windfall, Fluctuator, Time Spiral, Sneak Attack, Show and Tell, and Gaeas Cradle.
(I remember having a fluctuator deck that could win turn one. Fluctuator was banned right from the start however.)
All those cards needed to be banned or restricted due to how fast you could win. Sneak attack and Cradle werent banned or restricted but both were clearly staples and very good.
Not to mention cards like Morphling, who might not seem great now. But back then, he was about the best creature you could cast.
Thats just Urzas Saga. And there are many more cards im not mentioning that had a huge impact on all formats like Voltaic Key and Stroke of Genius.
Urzas Legacy was a great set to draft with and had great cards for its time. But overall that set was the weakest of the 3 in the block. Rancor, Tinker, Grim Monolith, Deranged Hermit, memory jar, Palinchron, and Treetop Village/Faerie Conclave. As you can see this list isnt quite on par with Saga.
Urzas Destiny was another one that over time doesnt seem like a great set. But it was BROKEN in its day. Masticore, Opalescence, Replenish, Yavimaya Hollow (was a crap rare back then basically), Academy Rector, Opposition, Treachery, Yawgmoths bargain, covetous dragon,Elivhs Piper, Pattern of Rebirth, Rofellos, and Plow Under.
It was the perfect cherry on top of the SICKEST block ever made. The constructed formats for standard and block were my favorite...still to this day.
When people get nostalgic about the Urza block its for a good reason! It was the BEST BLOCK OF ALL TIME. And its not even close.

Way too much easy and fast mana that fuelled way too many skilless value engines. Tolarian academy gave you more mana when you played artifacts that gave you mana by themselves. Tolarian academy also conveniently gave you the blue mana needed for your stroke of genuis.
You had worn powerstone, thran dynamo and grim monolith that could be played easily early with no real cost which partnered with tolarian academy to give you even more mana.
You also had draw engines like windfall and stroke of genuis that refilled your hand so when you were done ramping you could refill your hand and go searching for a wincon. You even had Yawghmoths bargain which people actually realised was better than Necropotence because you got the cards immediately. Yawghmoths Will being an incredible Snapcaster Mage for everything in your graveyard
You also had lands like city of traitors and ancient tomb that ramped you with no real cost as you would win long before a couple of shocks to the face mattered.

We are now playing magic cards.  We typically envision the scenario to be involved with summoning some creatures to attack or defend, casting some spells to hinder our opponents, setting up enchantments to boost up our advantages.  If our opponents don't do anything we play, a typical creature fast attack deck of all era probably wins on turn 4 or turn 5(if not, we need to redesign our deck).  What if we are playing against someone that does nothing to what you play, and suddenly wins the game on turn 2 or turn 3 or even the first turn?  The word "broken" is used to address such issues.  A lot of people don't want to play against such type of decks, but Urza's Saga block supplies numerous amount of cards that can make decks of this type.
What are the ways to win a Magic game?

One player's life drops to 0 or less.  (This is most common way to win.)
One player's deck is running out of cards, and he/she has to draw.  (The normal circumstance would be players have played for a long time.)
Certain cards dictates other winning conditions, and they have just been met.  (e.g. Coalition Victory)

In 2, if someone plays a game with 60 cards initially, and if you can force him/her to draw more than 60 cards at any turn, you win the game.  If you can do this on turn 1, you win on turn 1.  The cards in Urza's Saga block create such chance to become more likely to happen.  This concept is not seen in nowadays blocks because cards that can lead to this scenario will not be created, but if you play Vintage format, you will still see this.
Stoke of Genius forces anyone to be named to draw X cards.  If you have 60 mana for X, your opponent loses the game instantly.  Many decks in Vintage uses this method to win the game ----- generating a very large amount of mana in a single turn and then force the opponent draw to win.
Voltaic Key + Grim Monolith = 5 mana
Voltaic Key + 2x Grim Monolith = 7 mana
Tolarian Academy gives you 1 blue mana for each artifact you control.  Together with Voltaic Key and grim monolith, we can have a lot of mana.
Crop Rotation makes sure that even if you don't have any Tolarian Academy in your hand on turn 1, you can still scoop it up.  If you have 4x Tolarian Academy and 4x Crop Rotation, the chance that you can get a Tolarian Academy on the first turn increases from 40% to 65%.
Windfall/Memory Jar lets you draw 7 cards.  If you have less than 7 cards when you cast/activate, you gain cards.
Mind Over Matter + Tolarian Academy + many artifact in play + a lot of cards in your hand is a combo that can generate such a huge amount of mana.  Since Mind Over Matter is 2UUUU and Tolarian Academy generates blue mana, it's not difficult to cast early in the game.
Yawgmoth's Will allows you to play with less cards need to be drawn.
Yawgmoth's Bargain does not give you disadvantage if you play it early in the game.  A sudden draw of 10 cards makes combo decks work immediately.
Time Spiral almost work like giving you an extra turn because you get to untap 6 lands and refill your hand.
Tinker can be used to call up Memory Jar.
Frantic Search not only lets you have a chance to gain the card that you want, but also untaps lands.  If one of the land is Tolarian Academy, you gain more mana on that turn.
All those mentioned cards can be merges into a single extended deck.  Apart from Mind Over Matter, all mentioned cards so far belong to Urza's Saga block.  That's how powerful this block is.
I didn't mention how Tempest block and 6th Edition can help this type of deck.  Scroll Rack, Dream Halls, Enlightened Tutor, Mystical Tutor, Vampiric Tutor can speed up drawing.  Mana Vault is even cheaper than Grim Monolith.  City of Traitors and Ancient Tomb give you more mana early in the game.  Lotus Petal and Mox Diamond not only provide mana themselves, but also boost up Tolarian Academy.  Furthermore, they allow you to play non-blue spells such as Yawgmoth's Will and Yawgmoth's Bargain.
This type of deck is played like this:  You play Tolarian Academy + many artifacts, then you draw and draw and draw to give yourself more cards and more artifacts with Mind Over Matter in play(with 2 stroke of genius).  With almost your library becomes your hand, force you opponent to draw more cards than he/she has in their libraries for the win.  With Vintage format, from the help of power nine and Wheel of Fortune, if there were no restrictions on power nine and Wheel of Fortune, this type of deck finishes the game on turn 1 with probability at least 80%.  We rarely see a turn 3 or above finish.  If you are playing against a deck of the same type, it's almost like whoever wins the flip whoever wins the magic card game.  What is the need of playing magic card then?  Where is players' interactions during the game?  A lot of players would not play such a card game.
Tolarian Academy + Mind Over Matter is not the only way to generate a large amount of mana in a single turn.  Grim Monolith + Power Artifact, Worldgorger Dragon, Fastbond + Zuran Orb + Crucible of Worlds, and more other strategies can achieve.  All combo decks requires the components of combo to be met.  Yet the cards in Urza's Saga block mentioned in this article can also be used in other combo decks to speed up drawing just like Ancestral Recall.  Those cards appear in almost every Vintage deck.  They have perpetual effect in Magic.  If we have a new combo in the future, those cards will always be used.  Because of such versatility and such a large number of cards in a single block.  Urza's Sage is the most broken block throughout history.

I am certainly no guru, and I play MTG very casually compared to some. I think the reason the Urza block got mixed reactions was the introduction of some powerfully good cards, and the number of these cards, that these days (certainly in modern format that my group plays mostly) probably aren't that powerful at all! The game of MTG has changed over the years.
My group have fond memories of that block! Gaea's Cradle. Serra Avatar. Defence of the Heart. Congregate. Crazy days!

Not sure what you mean by this, " that these days (certainly in modern format that my group plays mostly) probably aren't that powerful at all" Do you mean that the cards from Urza aren't that powerful when compared to Modern cards of today?

Welcome to BCG!  Can you add some specifics?  Which cards are you talking about?


text:
Can I use a card with "Add one mana of any color to your mana pool" in any Elder Dragon Highlander (EDH) deck?
I recently tried Elder Dragon Highlander/Commander, and found it to be a ton of fun.  I've started customizing one of the pre-cons I got, but I'm a little confused by some of the deck-building requirements.
According to the deck-building rules:

A card's color identity is its color plus the color of any mana symbols in the card's rules text. A card's color identity is established before the game begins, and cannot be changed by game effects.
Cards in a deck may not have any colors in their identity which are not shared with the commander of the deck. (The identity of each card in the deck must be a subset of the General's)

If I'm using Animar, Soul of the Elements as my general, my deck's identity is Red, Blue and Green.  I couldn't use Crumbling Necropolis in my deck, because it has a black mana symbol in the rules text.
My question is:  can I add a card to my deck that has the phrase "Add one mana of any color to your mana pool" (such as Mox Opal or Ancient Ziggurat)?  Even though those cards could conceivably add black mana to my mana pool, they don't have a black or white (or any for that matter) mana symbol in their rules text, so they would be valid for inclusion in any deck?

In addition to the discussion of 'any color' below, I thought I'd point out that color identity only means mana symbols and not necessarily land names - so for instance, Verdant Catacombs is legal for your Animar deck because it doesn't provide black mana, it just has the phrase 'search for a swamp card'...

An interesting note is that you can run cards with extort in mono-black or mono-white decks since the extort cost is part of reminder text not rule text.

The text file found on the page you linked to with Commander info has a better description of the rules that clears this up. The important parts:

A card can't be included in your deck if any mana symbol in its mana
  cost or rules text is a color not in your commander's color identity.
  A card also can't be included in your deck if it has a
  characteristic-defining ability defining it to be a color not in your
  commander's color identity.

The cards don't have mana symbols, so you are good on that front. Yes, you could include those cards.
As of a January 18, 2016 change to rule 4, you can now use those cards to add any colour of mana to your mana pool, including Black & White mana if you're using Animar, Soul of Elements who has neither in its identity. Historically, if you tried to add a colour of mana to your pool that wasn't in your commander's identity, it would just add colourless mana instead.

First, you can only play cards within your commander's color identity. Second, you can only produce mana in said color identity. No longer true as of January 18, 2016 rules update. All players can have any color of mana in their pool, regardless of their commander's identity.
Mox Opal would be legal in any Commander deck, because it is colorless and "any color" is not a color identity. However, a mana rock like Obelisk of Esper, while colorless, specifically produces W, U, or B, so it would only be legal in decks whose commander has all three of those colors in it's casting cost.
It's noteworthy that the new Extort cards don't need commanders with both Orzhov colors; most you can consider only white, or only black. This is because the W/B mana symbol for the Extort cost is in the reminder text, not the rules text.

Since your question asks about "any" EDH deck, it's worth adding an answer about the case of a colourless identity general (since other questions have expressed uncertainty about the applicability of Charles' answer).
Clearly a Mox Opal would be a legitimate card for all the reasons already stated.  Other cards with similar wording/attributes follow logically.  When it  generates a coloured mana then, as in the coloured general case, the only relevant rule is

903.9. If mana would be added to a player’s mana pool of a color that isn’t in the color identity of that player’s commander, that amount of colorless mana is added to that player’s mana pool instead.

By 903.9 the coloured mana becomes colourless (the only available option with your general).No longer true as of January 18, 2016 rules update. All players can have any color of mana in their pool, regardless of their commander's identity.

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text:
How do you prevent deliberately losing in Republic of Rome?
In Republic of Rome, if Rome falls, everyone loses.  Some gaming groups I've been in grok this concept completely and players will make major sacrifices of their positions (donating lots of money from personal treasuries to the state to fight off the Punic Wars in the Early Republic, for example), while others regard Rome falling as a draw, and deliberately play to cause Rome to fall if they think they can't win.
If you have a mixture of both types of player, then the fall-of-Rome-is-a-draw players can exploit the fall-of-Rome-is-a-loss players by threatening to bring Rome down and demanding concessions for saving it.  This tends to provoke resentment on both sides.
Does anyone have any suggestions for (a) how to prevent this conflict and (b) how to resolve it before punches start being thrown?

Punches being thrown?  Wow, your group is way more hard-core than mine. :-)

Sounds to me like the game is just doing a better job of modelling senatorial politics than you realize.... :)

If it's not part of any sort of larger tournament or ranking system, then there's pretty much no difference between everyone losing and a draw, so it's just going to wind up being an issue of perception.
The solution, then, would be to play it in the context of a ranking system or tournament. I don't know the game in question, so I don't know what the possible outcomes are, but you could assign different point values to different results; winning gets you 1 point, losing gets you 0, and Rome falling gets everyone -1. Then people will have an incentive not to let Rome fall; if they do, they will lose rank compared to other players not in that game.
By the way, this sort of brinksmanship between the fall-of-Rome-is-a-loss and fall-of-Rome-is-a-draw crowds may be an intentional feature of the game. After all, it's not all that uncommon for some politicians or political parties to focus so hard on winning their own particular issues that they're willing to put the whole country at risk (state, nation, empire, what have you) if they don't get their way. It sounds like a pretty realistic political situation, if you ask me.

The fall-of-Rome-is-a-draw players are right: they realize that, like all games, it's a zero-sum game.
To solve this the other players should make sure that any players that can bring Rome down still have a chance of victory. They have power and deserve the concessions they ask for. It's very interesting from a game theorical perspective.

That makes sense to me from a game balance perspective - it forces the lead players to hold back, lest a player falls out of contention and tries to force a draw. (Put the other way, no matter how far behind you are, you always have the option of playing for the draw by forcing Rome to fall.)

It could be that the 'draw' players aren't thinking creatively enough; IIRC, the victory conditions become more fluid as crisis approaches (you can, for example, win by being in rebellion when the state goes bankrupt: presumably you then get called in, Monti-style, to sort out the mess). And if your position is strong enough for your actions to bring the country down, you should be able to finesse that into some chance of a win.
Perhaps more importantly, the game is about dirty politics; if the word 'Senate' doesn't make that clear enough, the history (turning a semi-democratic republic into an Empire with you in charge) should.  One of the rules of politics is always to keep the minor players happy (literally, in this case), so if the 'loss' players think the game's purely about building up votes and victories, they need an urgent re-think. You need to play so that everybody thinks they have a chance of winning, until your masterplan goes into action...

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text:
Cards entering the battlefield simultaneously and "Enter the Battlefield" effects
I was playing modern with the owner of a shop.  He played a Scapeshift which he used to bring in 7 lands: 5 basic mountains and 2 Valakut, the Molten Pinnacle cards.
He then claimed that each Valakut triggered 5 times (killing me).  I am doubting this now.
Here is my reason: The two Valakut cards entered at the same time as the other 5 basic lands.  That means when they were on the battlefield and their ability was in effect, the other 5 basic lands were already there too.  That seems too late to trigger a "Enters the Battlefield" effect.
So here is my question.  Am I right or wrong?  If I am wrong, please show me how the enter the battlefield effect can trigger for something that enters the battlefield at the same time as itself.
If I am right, please show me the rules that prove it.  I now have two shop owners that are convinced that this is a legal play.  If it is not legal, I am going to need clear rules citations to convince them.

Side note:  If I am wrong and it is a legal play, then I have a follow up scenario.  Say I have 2 Champion of the Parish cards and 5 other human cards in my graveyard.  If I play a spell that lets me return all of them to the battlefield at the same time (say Angel of Glory's Rise), would the Champion cards get 6 +1/+1 counters on them?
To me, if the trick that was played on me with Valakut is legal then my Champion cards should also get the +1/+1 counters.

@Rusher That question is about what order the various triggers happen in; this question is about whether or not cards see each other entering the battlefield when they enter at the same time. Though both are answered partially by 603.3b.

@Gendolkari In that case, this is a possible duplicate of Do creatures that enter the battlefield at the same time see each other enter?

@Rusher That one is similar; I linked it in my answer. But I don't think it's quite a duplicate.

Your opponent is correct, whenever multiple objects enter the battlefield at the same time, their enters the battlefield triggers will all see all of them as on the battlefield.

603.6a Enters-the-battlefield abilities trigger when a permanent enters the battlefield. These are written, "When [this object] enters the battlefield, ..." or "Whenever a [type] enters the battlefield, ..." Each time an event puts one or more permanents onto the battlefield, all permanents on the battlefield (including the newcomers) are checked for any enters-the-battlefield triggers that match the event.

And:

603.3b If multiple abilities have triggered since the last time a player received priority, each player, in APNAP order, puts triggered abilities he or she controls on the stack in any order he or she chooses. (See rule 101.4.) Then the game once again checks for and resolves state-based actions until none are performed, then abilities that triggered during this process go on the stack. This process repeats until no new state-based actions are performed and no abilities trigger. Then the appropriate player gets priority.

Note that the trigger happens AFTER the cards actually enter the battlefield. There is no time that Valakut was on the battlefield but the other Mountains weren't; so by the time Valakut's "enters the battlefield" triggers, they are all on the battlefield. If it did not work this way, any card such as Elvish Visionary that had "when [CARDNAME] enters the battlefield..." wouldn't work, because its ability doesn't technically exist until the card was put on the battlefield.
This is also a well-known combo for Valakut.
This means that this works for Champion of the Parish as well; the Champions would get 6 +1+1 counters in that case.
See similar question here.

Note that this is what allows cards like Elvish Visionary to trigger off of their own ETB triggered abilities.

@HaoYe Good point; I added that in.

603.6a is what I call a reminder rule. It's a redundant rule that makes it clear that another rule does apply in a certain circumstance. In this case, it's 603.6d: "Normally, objects that exist immediately after an event are checked to see if the event matched any trigger conditions. [...]"

@ikegami - I guess my confusion is not that Valakut would trigger, but that it would see the 5 mountains as having "entered the battlefield".  (It seemed that they were already one the battlefield just as surely as a land that was on the battlefield two turns earlier.  I have read 603.3b a few times and don't really understand it.  But it sounds like the "human readable" version of this is "If two or more permanents enter the battlefield at the same time, for each permanent, all the others are seen as having entered the battlefield after its self."  Does that sound right?

@Vaccano, it is tricky. I think to rephrase it in simple terms; the idea is that after things enter the battlefield, everything on the battlefield is checked to see if there are any ETB triggers. In this case, after the Mountains enter the battlefield, the game checks to see if anything triggers because they entered, and Valakut is there to be triggered now.

@Vaccano, A permanent see itself entering the battlefield. If two or more permanents enter the battlefield at the same time, each permanent sees each other enter the battlefield. (That's not a human-readable version of the rule; that's a specific application of the rule.)

@ikegami (and Gendolkari).  That makes sense.  If I view it from the point of the card entering the battlefield then it all becomes clear.  The Mountains enter then look to see if anything cares that they entered.  Since the Valakut cards are all there now, they both trigger.  Thank you both for clearing this up for me!

@Vaccano, yup, that's exactly what happens. Well put.

Both you and your opponent are incorrect :
Let us look at valakut wording :

Valakut, the Molten Pinnacle enters the battlefield tapped.
Whenever a Mountain enters the battlefield under your control, if you
control at least five other Mountains, you may have Valakut, the
Molten Pinnacle deal 3 damage to target creature or player.

This is what happens at the stack :
5 mountains + 2 valakut enters simultaneously, so there are 10 valakut triggers (5 mountains * 2 valakut).
Then, EACH mountain trigger check whether there's at least FIVE OTHER, BUT, there are not. There are only FOUR OTHER mountains, so it doesn't successfully deal 3 damage to you.
Hint : take a closer look at "OTHER".
Btw, tell the store owner : "you need 6 mountains + 1 valakut + opponent has 18 life or less to combo-kill at 7 lands".
And, this kind of effect check is CHECKED UPON RESOLUTION, so, it's never too late as you stated earlier.
Source : I play scapeshift competitively.

He just said that he brought in 7 lands with Scapeshift; he never said that there were no other Mountains still on the battlefield that weren't sacrificed by Scapeshift.

I won't assume something he didn't say.

Your answer does assume something he didn't say. You said his opponent was incorrect, but that would only be true if something you assumed was true (that there were no other mountains on the battlefield).

I can't tell if the other users are being purposefully obstinant, but OP is clearly implying the 5 Mountains brought in are the ones that meet Valakut's requirement.  Perhaps he could chime in to explicitly say so.

@user1717828 this was 2 years ago

lol, wow.  Guess that's what happens when you become a regular SE front page visitor and then suddenly end up on a page from a Google search.  Anyway, you're answer is painfully underrated.

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text:
Abilities that need a name and unnamed tokens
I am fairly sure on this one, but I wanted to ask to be really sure.
Say I have Secrets of Paradise and a deck with a lot of Rousing of Souls.
Am I right in thinking that because the tokens made by Rousing of Souls are just "1/1/ white Spirit" tokens (no name), there is no way for them to gain the tapping for mana ability that Secrets of Paradise can grant?

Actually, the tokens made by Rousing of Souls will have the name "Spirit" by 110.5c:

110.5c. A spell or ability that creates a creature token sets both its name and its creature type. If the spell or ability doesn't specify the name of the creature token, its name is the same as its creature type(s). A "Goblin Scout creature token," for example, is named "Goblin Scout" and has the creature subtypes Goblin and Scout. Once a token is on the battlefield, changing its name doesn't change its creature type, and vice versa.

However, as there is no card named "Spirit", you cannot name it for Secrets of Paradise (per 201.3).

201.3. If an effect instructs a player to name a card, the player must choose the name of a card that exists in the Oracle card reference (see rule 108.1) and is legal in the format of the game the player is playing. (See rule 100.6.) If the player wants to name a split card, the player must choose the name of one of its halves, but not both. (See rule 708.) If the player wants to name a flip card's alternative name, the player may do so. (See rule 709.) If the player wants to name the back face of a double-faced card, the player may do so. (See rule 711.) A player may not choose the name of a token unless it's also the name of a card.

Note that situations have occurred in the past, where "token names" have later been elevated to "card name" status. For example, in Future Sight, the white spellshaper, Goldmeadow Lookout made tokens named "Goldmeadow Harrier". At the time, you could not name "Goldmeadow Harrier" if an effect asked you to name a card. Sometime later, in Lorwyn block, Goldmeadow Harrier was actually printed as a creature card, which then did allow you name it if an effect asked you to name a card.

This is a very interesting / weird thing about MTG rules... these particular 2 cards can't work together, but if in the next set they created a card named "Spirit", suddenly this combo could work; even though it doesn't make much sense that it should have that effect.

@GendoIkari True, though I suspect that they regard basic token names as "taken" (in addition to being not really good interesting names) and will avoid doing that.

@Gendolkari: It actually did occur previously with Goldmeadow Lookout making tokens named "Goldmeadow Harrier"... which didn't show up as a card until a few blocks later!

@HaoYe Can you edit that into your answer?

@GendoIkari I agree that this is a dumb rule. The name of a printed card should have no effect on its functionality, or the functionality of other cards around it (maybe in an unset). Just let us name any name that we want.

@Cruncher I'm a big fan of Dominion, where the rules make it clear that you can choose to name "Ace of Diamonds" if you need to name a card.

@GendoIkari Actually, they couldn't generally (although Lore Seeker specifically in conspiracy could make this complicated) according to
201.3: "If an effect instructs a player to name a card, the player must choose the name of a card that
exists in the Oracle card reference (see rule 108.1) and is legal in the format of the game the player
is playing." I'm not sure of the ruling on whether Lore Seeker makes all cards ever printed in any set with boosters legal, or whether it only makes sets that were actually chosen legal.

@JakeP There are several formats for which a new card named "Spirit" would be legal in the same format as an existing card that has you name a card.


text:
Which is the authoritative ban list: MTGCommander.net or Gatherer?
I built me a Commander deck for Athreos, God of Passage.  I did some searching for ways to get  card draw (because I was running out of cards) and one of the card I looked at was Yawgmoth's Bargain.
I am always careful to check to make sure that the card I want to play is legal.  So I loaded the "Sets and Legality" tab for Yawgmoth's Bargain.  Since it is listed as legal for Commander, I bought the card and have been happily playing it in my Commander games.
Well, tonight I was browsing around and got to the Commander banned list (MtgCommander and Wizards).  To my surprise I saw Yawgmoth's Bargain on the banned list.
Frustrated that I had missed this I went back to the "Sets and Legality" page on Gatherer to double check.  As you can guess, the card is listed as "Legal" for Commander.
So, which one wins?  A ban list on a web page, or the Gatherer card database?
NOTE: I am happy to get opinions on this.  But what I really want is a rule to says which one is the authoritative source of legality.  (Without a rule, we are all just giving opinions right?)

I always thought it was common knowledge that Gatherer is not the authoritative reference for banned/restricted lists, but I've never actually seen an explicit statement indicating that. At least it's not in the comprehensive rules or the Magic tournament rules... beyond that, what sort of source would you consider authoritative? (see also this)

MTGCommander.net is the authoritative reference for all things commander.
Says who?
First, a little history.
According to this article, Adam Staley created the format. He shared it with Sheldon Menery, a retired Level 5 Judge, who popularized the format by inviting judges at tournaments to play. Over the next few years, the format spread from judges to the common player.
Gavin Duggan, who is a member of the Commander Rules committee along with Sheldon Menery, is also the creator of MTGCommander.net. When the rules committee bans a card, it shows up there first.
Wizards of the Coast catches on
But they wanted to avoid using the trademarked "Highlander" in the name (which could lead to a lawsuit), and so Wizards changed the name to "Commander". Wizards maintains the Gatherer and their own banned list for MTGO. Their list links to MTGCommander in the opening paragraph!

We like rules
If that wasn't convincing enough, there is actually a rule that acknowledges MTGCommander as the source of "additional resources" (emphasis mine):

903.1. In the Commander variant, each deck is led by a legendary creature designated as that deck’s commander. The Commander variant was created and popularized by fans; an independent rules committee maintains additional resources at MTGCommander.net. The Commander variant uses all the normal rules for a Magic game, with the following additions.

@ikegami; I find that to be a very unconvincing argument. I could go and put "This is the official page for MTG Commander rules" on my personal website right now; that wouldn't make it true. Also, Gatherer is the official webpage for MTG Oracle wording, which means that players will give a lot of weight to what it says on anything about MTG.

@Rusher - The addition of the rule is what tips it for me.  Since the rules don't (to my knowledge) indicate anything about banned cards, a rule saying to go check that site and that site says it runs the ban list, well that is enough.  Still I agree with Gndolkari.  The oracle for card text is on the gather website.  To have it be the source of truth for some card attributes and not for other card attributes seems ... odd at best.

@Vaccano I think they fully intend for it to be authoritative by proxy (it's a copy of the authoritative list, not something they made up), they just failed to copy properly, and they'll fix it eventually.

@ikegami How about we settle for this: Anyone who wants to "believe the page" can vote for your answer. Anyone who wants "circumstantial evidence" from a level 5 judge, a nod from the MTGO ban list, and the rule book can vote for mine.

You didn't mention any level 5 judge saying mtgcommander is official. There's no nod from the MTGO to the ban list. In fact, the MTGO ban list implies the MTGO list can be different than the EDH one. "Is based on" is very very different than "is a reflection of". The rule book doesn't mention anything about ban lists of any format. Why would they vote for your answer if they could vote for an answer that had these things you claim??? Unfortunately, they don't exist. If your answer was strong, you shouldn't have to lie about what's in it!

@GendoIkari, It wasn't suppose to be convincing. That was the point. It was as baseless as Rusher's. Nothing linked by the above says anything about mtgcommander.net being official or a source of rules for Commander either. It doesn't do anything more than acknowledge the existence of it. Just like SO acknowledges the existence of PerlMonks. That's not an endorsement. It's definitely not a hand off of control. That's all I was saying.

Neither. "The official banned list for commander games" is found on the EDH site, and it includes Yawgmoth's Bargain. Commander is just a reflection of EDH.
From the looks of it, DCI does not run Commander/EDH tournaments (since it doesn't have a ban list for it), but "Banned / Restricted Lists for DCI-Sanctioned Magic: The Gathering Tournaments" lists Yawgmoth's Bargain as banned in MTGO Commander games.

So what is listed on Gatherer is never authoritative?  How can you know that?  Is there a rule that says that the Gatherer page does not win when there is a conflict?  I get you don't think it can be any more definitive, but to me I see two pages (both on the Wizards site).  One says it is legal, and one says it is not.  How am I to know which one to believe?

Legal?  Because the Gather site says it is: http://gatherer.wizards.com/Pages/Card/Printings.aspx?multiverseid=15193

Well, It seems to me that the Gather is a web page purporting to show how the game works on the Wizards site.  It seems it would be just as authoritative as the ban list unless there is a rule that lists one as more valid than the other.

Ah, I think I get it.  The gatherer is just for "Commander"  The other page is the "Banned / Restricted Lists for DCI-Sanctioned Magic: The Gathering Tournaments"  So if I am playing in a DCI Sactioned magic event, then I need to not have Yawgmoth's Bargin in my commander deck.  But if I am just playing casual, then it is not banned.

Where does it say that it is not Authoritative?  It says more info can be found... but it does not say that it is not authoritative.

I was suggesting the page on the gatherer site says that it is for all types of the casual format Commander.  But if you end up in a sanctioned event....

I want to say that I really respect your opinion.  You answer a lot of magic questions on this site.  And I have never seen you be wrong.  Thank you.

Surely the Commander legality on Gatherer is intended to mirror the official list though? Seems like it might just be an oversight - though Sway of the Stars and Sylvan Primordial have the same issue.

@Jefromi, Of course it is suppose to be in sync. I have already reported the discrepancy.

@ikegami I misread your authoritativeness comment above, my apologies!

Ah..
Commander I see.
It depends on your play group then.
If you really wanna check the legality, I always look at magiccards.info. It's pretty reliable for me.
UPDATE :
It seems that I need to make some clarification for these downvotes :
I also mentioned a site which is reliable for me to decide legality of cards in a certain format. Which I believe, refer to the gatherer itself.
mtgcommander rules is also made based on community / certain play group. Bear that in mind before downvoting.
And, to asker, isn't it obvious that you need to "obey" the rules of the house above anything since WotC is the maker of the game? Everything else is subjective and community-made rules.

He's obviously not asking about the rules used by his playgroup but the official ones.

You obviously didn't read the magiccards.info part of my post.

No, I just didn't mention that it's wrong. And your update is making things worse. 1st para: Magiccards.info does not get its ban list from Gatherer, as you can see by looking at the very card being discussed. 2nd para: Doesn't seem to be saying anything. 3rd para: Actually, as obvious as you think it might be, it's wrong. WotC defers to mtgcommander.net for Commander.

The question is about authoritative lists, not house rules, and magiccards.info is not the authoritative list, though I assume it's a copy of it. (If it is it's out of date though. It says Sylvan Primordial is legal.) The downvotes are quite simply because people think you're wrong, and missing the point of the question.

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text:
What is a good opening in Blokus?
I have played Blokus enough times to get a feel for the game and one thing that always bugs me is how to play the first few moves.  There seem to be a couple of competing aims:

Get rid of big, awkwardly shaped pieces;
Create plenty of corners to leave lots of future moves open.

Assuming this is the case, which pieces are the 'most awkward', and does playing these achieve the goal of creating lots of corners?
Also, how many moves can you have before you have to start worrying about what other players are doing?
To help with answering this question here's a link to a picture showing a Blokus naming convention.

1, 2, 3, short I, I... O_o not a great convention.

The names for the pentominoes are fairly standard (http://en.wikipedia.org/wiki/Pentomino).  The names for the tetrominoes are almost standard (http://en.wikipedia.org/wiki/Tetromino) (the 'O' is referred to as square above).  The other four tiles are mainly distinguished by size, I guess the convention could have used the tromino naming convention for consistency (http://en.wikipedia.org/wiki/Tromino).

Ever since I learned about "the Barasona opening", I've had a hard time not starting all my Blokus games with it.
The basic idea is that your first four pieces leave no possibility for an opponent to move "through" your corner, without the use of his one-piece.
The pieces you use are F, X, W, and then N or Y.  You can see a picture of the Barasona in action here: http://boardgamegeek.com/image/112251/blokus.
Of course, the problem with the Barasona is that, while it provides a disincentive for other players to move towards your unprofitable corner, the moment the other players realize this they will probably all start using the Barasona themselves, and you're back to square one.  Blokus is an arms race!
Hope this helps!

I don't think the escalation you have proposed is certain. Against three Barasona's a single "farthest reach" opening will get access to all four quarters of the board without having to cross any of the Barasona lines.

My experience with Blokus is that it pays to not be confrontational. If the board splits into two 1v1 games, and players A and B are being confrontational and denying each other access wherever possible, and players C and D are being semi-cooperative and leaving gaps to work around each other, then players C and D will naturally get more of their pieces onto the board. If there's a region you've trapped all the other players out of, then you'll only be able to take advantage of about half the space. Whereas a region twice the size, shared between two players, can let both those players get twice as many of their pieces down, if they leave space for them.
So while I've encountered people using the Barasona opening, I don't use it myself. I find it pays far better to have fingers in as many pies (areas of the board) as possible, and not care who has fingers in my pies.
To this end, I try to run straight for the centre, and then extend tendrils towards any zones that are looking particularly contested. Specifically I'll start with (in some order) Z, V, W; sometimes amended to insert the X, which I often find hard to shift later on.
I also aim to have my first 12 plays be the 12 pentominoes. This often isn't possible - I'll want to get a finger into an area that needs me to use the 4-square line or some such - but when I do manage it, it leaves me very well set up for the late game.

If you can take advantage of 50% of the space in an area walled off by your own pieces, you're a VERY efficient blokus player.

I frequently get all my pieces down (4 of my last 5 games I think) by playing the I along the side of the board, then work Barasona style to the middle (though I'd not heard that term 'til reading this thread)

Be sure to take the strength of your neighbors into consideration when placing the I

My preferred opening is V W Z or V Z W. This gets you to the center of the board as quickly as possible, giving you potential access to the entire board. Any opening that concentrates on defense in the early game will be forfeiting access to at least 1/4 of the board.
The weakness of this opening is a very low ratio of corners to dead squares in your home corner, leaving you vulnerable to being walled in during the midgame if you have concentrated on the far side of the board.

I'm guessing that you mean V, W and Z played in the orientations to get towards the middle of the board?  While searching for an answer I saw somewhere that someone was suggesting starting with V then W in a heart shape, which seemed counter-intuitive to me.

Yes, this is the way I always try to play: use the pieces that touch diagonally opposite corners of a 3x3 square to get to the centre as fast as possible. I'll occasionally slow myself down slightly by including the X as 2nd or 3rd piece (not allowed to place it 1st) because I find that one particularly hard to shift later.

The opening you use is different if you are referring to playing a 4-player game, or a 2-player game (not duo, but the 2-player version on the full board).  I don't have much to say about the 4-player game, but if you're playing the classic-2 player version (C2), then this Barasona opening is actually very weak.  In a 2-player game, you should try to get both of your colours to the middle of the board as quickly as possible, and have them "connect" with each other, so they can cross over and share space with each other.
Even in the 4-player (which I admit I am not very experienced with) the Barasona opening actually seems really weak.  While you create a difficult situation for your opponents in your one corner, you don't expand much.  Generally expansion is better than defense.  Try starting with L, Z, W (all moving to the middle of the board as much as possible, never leaving a "v3 hole" in your pieces.

+1 Thanks for this answer.  I was actually interested in the four player game, but will definitely have to try playing with two at some point!

what's a "v3 hole"?

V3 refers to the piece with 3 squares, which is in the shape of the letter V. The 3 distinguishes it from the larget piece of the same shape, which is called V5 or just V.  A v3 hole then is a set of open squares surrounded by other pieces which has that shape.

I always try to use the largest farthest reaching pieces at the beginning to reach the center, and then go to stake out space.  If everyone is doing a similar thing, I don't worry about them until we meet.

I've found a particularly effective 3 move opening in Blokus is to play two of the most linear pieces first, head straight for the center of the board, then on your third move play the big cross piece as near to the center of the board as you can. Then radiate out in all directions. Using this tactic ive observed that by the end of most games i dont generally dominate any one region of the board, but my pieces have infiltrated all my opponents territories like a virus across the whole board.
john m

So when you say 'linear pieces' I think of the straight ones, but those don't get you towards the center of the board. Do you mean the ones that get you the closest to the center?

In the - admittedly few - games of blokus I've played so far I found it to be easier in the long term to be confrontational: i.e seeking to wall in at least one opponent.
As a consequence to that strategy I try to get to the middle as fast as possible and then head towards one of my neighbors.

For loads of information about openings and play after the opening,
refer to a blog written by a champion player (blokusstrategy.com)

when you play more, you'll realize what pieces are unwieldy and which others are not so much. By general consensus, the 5 pieces are obviously the hardest to add upon later on, thus, you must play them first if you can. And of course, out of the 5-piece blocks, there are the worst, which people above clearly have the consensus to be V, W, and Z. Of course, the 5-straight line can be also useful in the beginning to open up and quickly reach the center, and the X can also be difficult to throw in the later game. When opening up you should also consider how to block off your opponent's advances so they don't get into your territory.

Use the 'W' shape piece first or second move.

Hey there.  While this might be a valid answer to the question, it would be a lot better if you tried to add some context to the answer.  Possibly say why using that piece is better at the start?

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text:
Does Strionic Resonator cause Medomai, the Ageless to let me take 3 turns upon hitting someone?
We are playing commander and Medomai the Ageless is my commander. If I use Strionic Resonator on the triggered ability to take an extra turn, it adds two instances of take an extra turn so it should give me 3 turns right?

a little confusing how it's worded, taking 3 turns rather than taking 2 extra turns.

Yes, extra turns can stack in this way.

500.7. Some effects can give a player extra turns. They do this by adding the turns directly after the specified turn. If a player is given multiple extra turns, the extra turns are added one at a time. If multiple players are given extra turns, the extra turns are added one at a time, in APNAP order (see rule 101.4). The most recently created turn will be taken first.

Yes, Medomai's ability is triggered and can be copied with Strionic Resonator, giving you 2 extra turns.

603.1. Triggered abilities have a trigger condition and an effect. They are written as “[When/Whenever/At] [trigger condition or event], [effect]. [Instructions (if any).]”

Thanks i was confused as to whether the turns add on to one another giving multiple turns or just 1 turn


text:
MTG Arena: Enter battlefield ability denied by killing the creature causing it?
I played Acquisitions Expert in MTG Arena. My opponent reacted with Stomp adventure of Bonecrusher Giant and killed the Acquisitions Expert. Even though I saw my Acquisitions Expert's ability still being on the stack after Stomp resolved, Acquisitions Expert's ability did not resolve and opponent did not have to discard a card. Why did this happen? I just can't figure it out.

It should have resolved.  But a crucial part of that would be knowing how many creatures were in your party when it resolved.  If the Acquisitions Expert was the only one and was dead when the ability resolved, the ability won't do anything useful (reveal 0 cards and discard 1/0 cards = discard nothing).

@Becuzz That it is! I did not consider that when the ability came to be resolved, the Acquisition Expert was no longer in play so the party was indeed 0 in size and thus empty trigger was skipped instead of showing me 0 cards to choose from. Thanks!

@Becuzz That would be good to post as an answer.

@eXPRESS technically the trigger did resolve (would matter for anything that cares about that, can't think of anything) but MTGa auto chooses target opponent since there's only one, and because it asked to reveal 0 cards and discard 1 out of those 0 the game auto handles things where no actual choices need to be made - but for purposes of anything that might care about triggered abilities resolving, it didn't actually fizzle or skip the trigger, it just resolved behind the scenes doing nothing.

@Andrew Yeah, you are right I did not word it properly, by skipped I meant auto resolve.

It should have resolved. But a crucial part of that would be knowing how many creatures were in your party when it resolved. If the Acquisitions Expert was the only one and was dead when the ability resolved, the ability won't do anything useful (reveal 0 cards and discard 1 out of 0 cards means discard nothing).

The Expert makes your opponent reveal cards equal to the amount of creatures in your party, you then choose one of the revealed cards to discard. What often happens when you play the expert on turn 2, is that you have no other creatures in your party.
What then happens is if your opponent is savvy is that he kills the expert in response to its trigger. This leaves your party empty when the ability resolves, meaning you reveal 0 cards and making it impossible to choose a card to discard.


text:
What's the cheapest way to buy a large number of Magic: the Gathering cards on Cardmarket?
I need cards for my new EDH decks and I want to buy them on cardmarket.com. They have this neat feature called the Shopping Wizard, which does all of the work for you. Last time I needed around 60 cards and I ended up buying from four different sellers to get all the cards in the most cost-efficient way.
The way the Shopping Wizard works is to try to combine low-cost cards in a way that minimizes both card cost and shipping costs. Since shipping costs tend to be fixed per seller, it is typically beneficial to have as few sellers/packages as possible.
Problem is, the Shopping Wizard can only handle lists of up to 150 cards. And I need 250.  So I will have to use the power of the Shopping Wizard algorithm at least twice. But I don’t know how to proceed. I sorted the cards by price, with the most expensive card on the list at about 15€ and the cheapest one just 0,06€. My goal is to minimize the overall cost of this purchases (including shipping). So now I don’t know if I should start with the 150 most expensive or cheapest cards. (Or some other combination).
Buying lots of really cheap cards usually results in few (or even just one) recommended sellers. Maybe I could get those cheap cards from someone else even cheaper, but less sellers means smaller shipping costs. A list with more expensive cards usually gets divvied up between multiple sellers. This obviously increases shipping costs, but if someone sells a card for way less than everyone else, it might sometimes be best to buy just one card from them.
In an ideal situation, all 250 cards would be split into groups for cheapest total cost, and then I would just have 2 orders based on those groups. But since I can't know the groups, I want to minimize breaking up the groups and causing more packages & shipping cost.
So my question is:
What’s the cheapest way to buy more than 150 cards of varying price levels on cardmarket.com?

How is this advertising? I didn't say that anyone should buy their cards there. Nor did I say that the cards on cardmarket are the cheapest or that the service itself is good. I'm asking if some can help me optimize the process of buying something. That's not how advertisement works.

How would buying 250 cards on the site at once with the wizard and 250 cards in two batches using the wizard not give you the same price? The way I read this question is you are trying to advertise a feature of a shopping site by phrasing it as a question. My main concern is that there is no way buying cards in separate transactions is going to make the card cost more or the fees from the transaction cost more instead of buying them in a single.

Why are y'all treating this like spam? Sure it might ping our spam radar for a moment, but it's not spam, and we should assess it as such. Cardmarket doesn't even need the advertising. It's already the primary card marketplace in Europe with basically no real competition out here. And because it's the primary card marketplace in Europe, people in Europe are going to have questions about how to operate it—and we should be able to facilitate those questions without responding to it with hostility as spam.

I could see the case for it being off topic, in that it's about how to use a shopping site and not about the game itself. It's not definitively off topic, but I'd say there's like an 80% chance it is. But it definitely isn't spam - I'm convinced it's a real problem faced by a real person, not some weird astro-turfing attempt by CardMarket. I mean, if I was going to astro-turf, I wouldn't do it by highlighting a deficiency in my product.

@JoeW I can think of three reasons why the price may differ, the smaller reason is rounding on bulk (sub cent cost) items and tax percents to full currency but that's only a few cents of difference and the bigger reasons I can see are shipping costs (multiple orders, multiple shipments to pay for) and bulk discounts (5% off orders over $100, or over 200 cards or whatever) With these 3rd party seller sites that discount is less likely, but more shippers means more shipping costs.

I see this as off topic, it's an optimization problem and the answer is unfortunately VERY specific to who's offering what at what price and has just too many variables to be solved by pure math (which would, if it could be, fit on another SE better I'd argue anyways)

@Andrew I agree that there are many reasons why it can differ but explaining that in the question would help

There's a reason they limit the number of cards per batch - (price) optimization is one of the most complicated and time consuming things in computers, every thing you add to it makes the system recheck (nearly) every possible combination to find the best price, and the time it takes to do that is exponential. so eventually adding one more time would be the difference between seconds and minutes, or minutes and hours to re-calculate. 150 each is already a lot of items.

I've reopened this and cleared spam flags. If you think you have evidence this is spam (i.e. that the primary purpose is advertisement and not to ask a question, or that the author has an undisclosed affiliation), feel free to raise an additional flag, or ask for clarification on [meta]. But simply mentioning a retailer does not constitute spam, and treating questions of that sort as spam is hostile. We do not do that here.

There is no definitive answer to this. I've come across this problem myself and thought about it for quite a while to try to come up with a heuristic and/or reasoning.
In the end it depends how much time you want to spend. I believe I ended up using the 150 most expensive cards (or rather the cards above the ~0.10€ to 0.20€ threshold because below that everything is irrelevant) and sent those to the Shopping Wizard. Then I went through those five sellers and checked every one for the other missing cards (saved in a second Wants list of course). Here you have to cross-check etc but sorting by price and name worked for me.

Exactly.  The highest price volatility is with the most expensive cards, grab those as efficiently as possible, and toss in the low cost cards from any of the sellers in your order that have them.  You might pay a couple of extra Euro, but your time has value as well....

The shopping wizard optimises your order, and it may sound simple but the way a computer handles that can be really complicated, and gets much more complicated the more items it needs to consider. There's a few things you can do that might help, but they won't guarantee the absolute lowest price (the way optimising all 250 through the system at once would). I also am not European and have not used card market for buying cards, I do not know the system so some of these may not be possible.

Don't split piles of the same card - If you need say 20 copies of Sol Ring, don't buy 10 in one order and 10 in the other. The only time you should split them is when they fall into tip 2, and that seller doesn't have enough inventory to fill your whole need.
Make a single order out of the few most common sellers returned by the wizard. (if it tells you what you're buying from who)

Make a full order of 150 cards, and if you can group by seller.
Write down all cards being sold by the top few sellers (hopefully ~100 cards) then remove them from the order.
Add the rest of your buylist, noting any cards that come from the same sellers
Make an order out of ONLY those cards you noted in 2 and 3.
Let the system optimise the other 100-150 cards on your second order as best it can

"Write down all cards" If OP can get a scraping tool, and feed the data into a computer program, that will make things a lot easier.

@Acccumulation true, i was going for low tech basic tips, you could screensgot tge lists too, how you pull the data from the results set isnt as important

A little far fetched, but if a lot of the cheap cards are for example commons or uncommon from the same set. You could buy the whole common set from it, even when not needing/wanting some cards from that. If this is the case you can get a lot of the cards for a low price and with that shorten your list.
Another way (and a bit time consuming) is to shuffle the list a few times, (throw some in and out) and see if there is a seller which comes forward most of the time. Then you can go to this seller specifically and handpick the cards there. This way it will be bundled in one sell/postorder.


text:
Rummikub: Initial meld with a joker
The following tiles are on the table (these were the initial meld from another player):
10 BLUE, 11 BLUE, 12 BLUE
And I, having not yet made an initial meld, have the following tiles on my board:
7 BLUE, 8 BLUE, 9 BLUE, JOKER, 13 BLUE
I use the first four tiles to make my initial meld.
Questions:

Am I allowed to play other tiles in the same round that I played my initial meld?
Am I allowed to add my 13 BLUE to the other player's run, take the 10 BLUE to replace the JOKER in my initial meld, and re-use that JOKER, all in the same round?

I've never played this game but reading rules here it seems clear enough.  The rules say (emphasis mine)

In order to place tiles on the table, each player must make an initial
play of at least 30 points in one or more sets.
These points must come from the tiles on the player's rack and not
from tiles already played on the table. A tile is worth its face
value. A Joker may be used for any tile and its point value is that of
the tile it represents. The penalty for holding a Joker if another
player wins the round is 30 points. If a player cannot enter the
round, or purposely chooses not to, the player must take a tile from
the pouch and the turn ends.
After players have made their initial plays, they can also build on
other sets on the table with tiles from their racks.

so 1) No you are not allowed to play other tiles the same turn.  The rules are clear that you must use your own tiles and not other players.  It isn't until after all players have made an initial meld or passed you may start building off other players.
The rules for jokers state

A joker can be retrieved from a set on the table by a player who can replace it during his turn with a tile of the same numerical value and color it represents. The tile used to replace the Joker must come from a player's rack and not from the table.

So you can't reuse the joker since the 10 Blue was not in your hand.


text:
How does color identity work in Commander?
I recently began playing commander, and have run into a few questions, mainly about color compatibility with a commander. I think I can lump them all together into this one question:
What exactly determines color identity in cards?
And then just a few specific examples to make sure I'm understanding this correctly:

If my blue commander has an activated ability in non-blue color(s), what colors can I run in the deck? e.g.: Shu Yun, the Silent Tempest

For a mono-blue commander deck, can I have a card with a non-blue color(s) activated ability in the deck? e.g.: Cloudheath Drake

For a mono-blue commander deck, can I include in my deck a card with a hybrid mana cost that can be cast with either blue or non-blue mana? e.g.: Covetous Urge

For a mono-blue commander deck, can I have a card that makes non-blue mana? e.g.: Iron Myr

That's several questions.  Please ask one per post.

It's really only one question: 'what is color identity?'

@Chenmunka It is one question "What exactly determines color identity in cards?" with multiple examples that go at different parts of the rules for determining color identity.

related: https://boardgames.stackexchange.com/questions/14175/are-there-any-edh-commanders-whose-colour-identity-is-not-solely-determined-by-t/54059#54059

The color-related deckbuilding rules of Commander are centered around a specific characteristic named 'color identity'
Color identity is distinct from the color of the card itself, which is only determined by the mana cost and color-defining abilities

903.4. The Commander variant uses color identity to determine what cards can be in a deck with a certain commander. The color identity of a card is the color or colors of any mana symbols in that card’s mana cost or rules text, plus any colors defined by its characteristic-defining abilities (see rule 604.3) or color indicator (see rule 204).
Example: Bosh, Iron Golem is a legendary artifact creature with mana cost {8} and the ability “{3}{R}, Sacrifice an artifact: Bosh, Iron Golem deals damage equal to the sacrificed artifact’s converted mana cost to any target.” Bosh’s color identity is red.
903.4a Color identity is established before the game begins.
903.4b Reminder text is ignored when determining a card’s color identity. See rule 207.2.
903.4c The back face of a double-faced card (see rule 711) is included when determining a card’s color identity. This is an exception to rule 711.4a.
Example: Civilized Scholar is the front face of a double-faced card with mana cost {2}{U}. Homicidal Brute is the back face of that double-faced card and has a red color indicator. The card’s color identity is blue and red.
...
903.5c A card can be included in a Commander deck only if every color in its color identity is also found in the color identity of the deck’s commander.
Example: Wort, the Raidmother is a legendary creature with mana cost {4}{R/G}{R/G}. Wort’s color identity is red and green. Each card in a Wort Commander deck must be only red, only green, both red and green, or have no color. Each mana symbol in the mana cost or rules text of a card in this deck must be only red, only green, both red and green, or have no color.

What this means is that if a mana symbol appears on a card, it is part of that card's color identity. It doesn't matter if the symbol is in the mana cost, an ability cost on the card, or is produced by an effect of the card.  If the card has rules that grant it other colors (like Transguild Courier) then it has those colors as well. The exception is if that symbol appears in reminder text: Trinisphere still has a colorless identity, and Crypt Ghast still has a mono-black color identity.
If a card has a color identity that includes a color that is not part of your commander's color identity, it cannot be added to your deck.
To address your specific examples:

Shu Yun has a WUR color identity.
Cloudhearth Drake has a WU color identity
Covetous Urge has a UB color identity
Iron Myr has a R color identity.

It's worth noting examples of reminder text is not being considered part of the card for the purposes of color identity. The most notable example of this is Extort, even those that include the printed reminder text, to have W or B color identities, not always WB. Crypt Ghast can be in mono black EDH, Blind Obedience can be in mono white.


text:
How does white win this capturing race?
I'm reading "Sabaki, the art of settling stones" by Richard Bozulich. On page 98, it proposes the following solution for white to settle his stones. The explanation reads "after the moves to 9, it is clear that white wins the capturing race."

I don't see at all how white wins this capturing race, especially since it is black's turn now. As black I would just connect under after which I see no way for white to capture the three black stones. Am I missing something or is this just a mistake?

I wonder if there is a copyright problem with reproducing an entire problem and its solution. That said, I fired up Lizzie+KataGo, and they agreed with you about connecting underneath at T15. Instead, it seems that 9 should be played at T15 to win the fight, but again 8 should be at P13 to win it. Also that 6 was correct, so 7 should have retreated to Q11. etc. etc.

This seems like a mistake to me. I don't see a way to win the race. I wonder if the point was that White now has a stable group, so this is a failure for black. White can hane underneath the stone on the right side, and should probably be happy with that - Black was stronger here to begin with.


text:
Ordeal of Nylea and the stack
I was playing MTG with my lady and came across this scenario:
She had a creature with 2 +1/+1 counters, and 2 Ordeal of Nylea.
She attacks with the creature, both triggers hitting the stack.
I play Murder while the triggered abilities on the stack, killing the creature.
Since the creature isn't around anymore, I believe the triggered abilities will fizzle, meaning she doesn't get the lands as no +1/+1 counters are placed as the creature is dead.
Can anyone confirm my resolution?

Your opponent does not get the lands. When the Murder resolves, this rule comes into effect:

303.4c If an Aura is enchanting an illegal object or player as defined by its enchant ability and other applicable effects, the object it was attached to no longer exists, or the player it was attached to has left the game, the Aura is put into its owner’s graveyard. (This is a state-based action. See rule 704.)

The two Ordeals are placed in the graveyard. Then the +1/+1 counter triggers resolve (though no counters are actually placed on anything), but there's no Ordeal to sacrifice and so the second ability never triggers.

Your conclusion is correct: no counters will be placed, and the creature's controller will not get any lands.
Strictly speaking, each Ordeal's first triggered ability does not "fizzle". They still resolve as always, but the actions they try to take are impossible so they don't actually do anything. The creature is dead, so no counters can be placed on it, and the Ordeal is already in the graveyard, so it can't be sacrificed.
Since the Ordeal can't be sacrificed, its last ability cannot trigger, so the player can never get lands in a scenario like this.

Your opponent will not get to sacrifice Ordeal of Nylea or search for lands.
Although an ability does still resolve if the source leaves the battlefield, in this case, that ability resolving will not cause all of its effects to happen.
The triggers from Ordeal of Nylea will still resolve even though the source has left the battlefield.

112.7a Once activated or triggered, an ability exists on the stack independently of its source. Destruction or removal of the source after that time won’t affect the ability.

So you will still follow the instructions on the ability:

put a +1/+1 counter on it [the creature that attacked].

This instruction will not do anything because the creature is not on the battlefield anymore.
You will then go to the next instruction:

Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Nylea.

This will check how many counters were on it when it was last on the battlefield, which is only 2, so it won't pass the check.

608.2g If an effect requires information from the game (such as the number of creatures on the battlefield), the answer is determined only once, when the effect is applied. If the effect requires information from a specific object, including the source of the ability itself, the effect uses the current information of that object if it’s in the public zone it was expected to be in; if it's no longer in that zone, or if the effect has moved it from a public zone to a hidden zone, the effect uses the object’s last known information.

Even if all that weren't the case, your opponent would be unable to sacrifice Ordeal of Nylea because it is already in the graveyard by the time they are instructed to do so.