text:
What happens if a slapped player plays a card before playing a Slap
Say Alice plays a Double Slap targeting Bob.
Say Bob plays a card, which accepts the Double Slap. Then, Bob plays a Double Slap targeting Chuck, ending their first turn. Bob then plays a Skip for their second turn.
Would Chuck be able to play a Double Slap to pass on the slaps to Darlene x4, or do they have to take the double turn since the Double Slap was not the last card played?

Double Slap reads:

End your turn and make a player take any other turn you have plus two more.

When you play a Slap card, your turn ends and all your remaining turns are transferred to the slapped player. That means the second player illegally played Skip when it wasn't their turn in your example.
What should have happened:

Alice plays a Double Slap targeting Bob. Play transfers to Bob, which must play 2 turns (as per the text on the card).
Bob plays a card (thus taking a turn instead of responding to the Slap with a Nope or another Slap).
Bob plays a Double Slap targeting Chuck. Play transfers to Chuck, which must play Bob's remaining turn plus two more, for a total of 3 (as per the text on the card).
Chuck responds with a Double Slap targeting Darlene. Just like playing Nope, this is played out of turn. Play transfers to Darlene, which must play the 3 turns Chuck would have had to play plus two more, for a total of 5 (as per the example in the rules).


text:
Thornbite Staff and mana cost
With Thornbite Staff, do you need to pay two mana to untap this card if a creature is put into the grave yard or is the mana cost only for doing one damage to target creature or player?

The mana cost is only for the first ability, dealing the damage.
Thornbite Staff gives the creature 2 complete separate and unrelated abilities. The first is an activated ability; because it has the format {cost}:{effect}. The second is a triggered abilitty, because it starts with the word “whenever”. Each ability is surrounded separately by quotes, with “and” in between.

source: Stack Exchange

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sort: votes


text:
When playing with Unstable cards when and by whom the distance metrics is chosen?
I know this question might sound crazy but as defined on card Just Desserts the π is equal to the ratio of (let's suppose unit) circle's circumference to its diameter. But nowhere is specified how the distance is measured.
As far as I know, there are many ways how the distance might be measured and by choosing the distance metrics the value of π might be chosen basically arbitrarily. In Euclidean metrics, it is of course 3.141592... but in Manhattan metrics, for example, π is equal to 4.
Strangely enough, there exists metrics where π is infinite. Roughly speaking the metric is as follows: The point has 0 distance from itself, the distance between every other two points is the same and equals to 1. Therefore the unit circle contains all other points except its center and if we're assuming the space contains an infinite number of points, the value of π is by definition infinite.
By whom and when is the metric chosen?

I think you are misunderstanding the role of reminder text on MTG cards. It is not a definition that overrides anything else. It is simply a reminder of any information that is not explicitly stated. In addition, you seem to have read only part of that card's reminder text, because the second part states a specific numeric value.

I think it's important to point out that this question is based on a bad premise, namely that π is shorthand for "ratio of a circle's circumference to its diameter" - that's not correct. As the answer points out, π is a mathematical constant which always has the value 3.141592....

π refers here to the mathematical constant that has the approximate value 3.14
The reminder text on Just Desserts says

It's a smidgen more than 3.

and one of the rulings says

If the damage from Just Desserts gets redirected to a player, use 3.14.

On a more general note, when the symbol "π" is used to refer to a number in mathematics, it always refers to the ratio of the circumference of a circle to its diameter in Euclidean geometry. You can see this in the Wikipedia article, the Wolfram Mathworld definition, and others.

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text:
Resource Monopoly when player only has one of the named resource
Does the opponent have to give you the selected resource ONLY if they have 2, or do they have to give the selected resource EVEN if they have only 1?

They must give the one they have.

This is covered by the rules.

Resource Monopoly
Name a resource. Each player must give you 2 of that type of resource if they have them.
You may name any of the 5 resources (ore, grain, wool, lumber, or brick). Each player must give you 2 of the named resource if he has them. If a player only has 1 of that resource, he only gives you 1.

It's basically a version of the original game's Resource Monopoly (which forced other players to give the user all of their cards of the named resource) that has been capped to two cards.


text:
Can 'whenever' abilities trigger multiple times per turn?
Let's say that I have an Utvara Hellkite and 3 other dragons on the battlefield. Do I get a 6/6 Dragon for every Dragon that's attacking, or just one?

Someone has the Draconic Domination deck :P

Be careful using the word "activate" here. The proper question is "does it trigger multiple times"? To "activate" an ability is something you do to activated abilities, which are abilities with a cost, not a triggering condition.

They can trigger more than once, but whether they do or not depends on the specific wording. "Whenever a Dragon you control attacks" triggers for each attacking dragon, while "Whenever Dragons you control attack" only triggers once.

On the card it says you get a 6/6 dragon token whenever a dragon you control attacks.

112.3c Triggered abilities have a trigger condition and an effect. They are written as “[Trigger condition], [effect],” and include (and
  usually begin with) the word “when,” “whenever,” or “at.” Whenever the
  trigger event occurs, the ability is put on the stack the next time a
  player would receive priority and stays there until it’s countered, it
  resolves, or it otherwise leaves the stack. See rule 603, “Handling
  Triggered Abilities.”

So every time the trigger event occurs. But you can't activate abilities when attackers are being declared.

603.2a Because they aren’t cast or activated, triggered abilities can trigger even when it isn’t legal to cast spells and activate
  abilities. Effects that preclude abilities from being activated don’t
  affect them.

There are two types of abilities (that use the stack): activated abilities (which can also be loyalty abilities) and trigger abilities. Trigger abilities can trigger whenever; hence the word whenever/when.

603.2c An ability triggers only once each time its trigger event occurs. However, it can trigger repeatedly if one event contains
  multiple occurrences. Example: A permanent has an ability whose
  trigger condition reads, “Whenever a land is put into a graveyard from
  the battlefield, . . . .” If someone casts a spell that destroys all
  lands, the ability will trigger once for each land put into the
  graveyard during the spell’s resolution.

For every occurrence. Even if no one can react between those occurrences.
So you get as many dragons as you attack with.

For extra clarification, if the ability were to create one dragon even if you attack with multiple, the wording would be "Whenever you attack with one or more dragons...", or something similar.


text:
Can an enchantment creature with hexproof be targeted by destroy target enchantment card?
Can an enchantment creature with hexproof be targeted by a spell that destroys enchantments. For example, can Archetype of Endurance be targeted by Naturalize?

No. Hexproof prevents something from being targeted by opponents' spells and abilities — that's pretty final. You can't target Archetype of Endurance with Naturalize because you can't target it at all; there's nothing special about enchantment removal.
(If you're thinking hexproof is a creature thing, and we're getting around it by targeting their enchantment-enss instead of their creature-ness, that's not how things work in M:tG. Note also that anything can have hexproof: enchantments, players, or even every permanent you control.)
You get around this by doing things that don't target the creature: Dead Drop, Toxic Deluge, Settle the Wreckage, are examples of the kinds of non-targeting effects you'd use, or a plain old Wrath of God effect. Or kill it in combat.


text:
Koth of the Hammer (-2 ability)
Will the mana that has been added to your mana pool by Koth of the Hammer's -2 ability empty as your turn ends, or is the mana from the -2 ability added for the rest of the game?

Mana empties from every player's mana pool at the end of each step and phase.

500.4. When a step or phase ends, any unused mana left in a player’s mana pool empties. This turn-based action doesn’t use the stack.


text:
Can a single event trigger more than one triggered ability?
Heart-Piercer Manticore has an ability that reads “When Heart-Piercer Manticore enters the battlefield, you may sacrifice another creature. When you do, Heart-Piercer Manticore deals damage equal to that creature’s power to target creature or player.”
If you cast two of these creature spells and then sacrificed one creature would that trigger the abilities for both creatures as they enter the battlefield?
Second example is two permanents say the same thing; “Whenever an opponent loses life, you gain that much life.”  So would the event the opponent loses life trigger both permanents so you would gain two life , or would the event only trigger one meaning you would only gain one life?

Yes, a single event can trigger more than one trigger, but you are misunderstanding how Heart-Piecer Manticore works.
Your second example is a good example of this. If you have 2 Soul Wardens on the battlefield, then each one will trigger when a creature enters the battlefield, and you will gain 2 life. Or if you control 2 Bloodbriars and find a way to sacrifice a permanent, both of them will trigger and they will each get the counter. Note that while both trigger at the same time, the 2 abilities are placed on the stack separately and resolve one  at a time.
However, your first example is a different thing. The "when you do" in Heart-Piercer Manticore's ability is not simply “when you sacrifice a creature”, but rather it is part of the “when Heart-Piercer Manticore” enters the battlefield.” ability. When that trigger resolves, you can choose to sacrifice another creature to create another trigger to deal damage; but you are only in the middle of resolving one "enters the battlefield" trigger.
You can only cast creatures one at a time, and you cannot sacrifice the same creature twice.
The sequence of events would be this:

Cast Heart-Piecer Manticore.
It resolves and enters the battlefield.
Its ability triggers and goes on the stack.
Its ability resolves, and you sacrifice a creature to trigger the when you do trigger. (Or chose not to, and the ability does nothing).
The when you do trigger resolves and you deal damage.
Cast another Heart-Piecer Manticore.
It resolves and enters the battlefield.
Its ability triggers and goes on the stack.
Its ability resolves, and you sacrifice a creature to trigger the when you do trigger. (Or chose not to, and the ability does nothing). The creature you sacrificed the first time is already dead, so you need to choose a different one this time. You could choose that first Manticore if you wanted.
The when you do trigger resolves and you deal damage.

So by the time you are casting a second Manticore, it is far too late to deal with the first one's triggered ability. That will have already finished, and you will have either sacrificed a creature for damage or not. If you want to do it again, you have to sacrifice another creature.
Note that even if you used some other ability to place both Manticores on the battlefield at the same time, that wouldn’t matter. Each one would trigger at the same time, and you would choose the order to put the triggers on the stack. They would still then resolve one at a time, and you would have to choose to sacrifice a creature for the ability one at a time.

@ikegami I see, I misread the "when you do" as "if you do". Maybe I should ask a separate question; but is there a particular reason why an ability would use this format over "if you do"? Seems strange to simply create a separate, second trigger rather than just resolve it there and then.

It would be weird to have an ETB that targets. 2) It's effectively a damage-dealing activated ability ("Sacrifice another creature: Heart-Piercer Manticore deals damage equal to that creature’s power to target creature or player.") that's only usable when HPM ETBs, and as such, the affected player should get a chance to respond. If it was "If you do", the affected player would have to respond before you decide to "pay the cost", which would be very unusual.

@ikegami Regarding #1... tons of ETB triggers target? Snapcaster Mage, Abyssal Horror, Acid Web Spider. But regarding #2, point taken. I guess the ability would be stronger the other way, because this way the opponent can wait until you've sacrificed the creature before doing something that nullifies the damage.

Yeah, #1 retracted :) And the now-obsolete comment has been deleted.

Yes, a single event can trigger more than one triggered ability.
For example, if you had two Exquisite Blood on the battlefield, both trigger on an opponent losing life, so you will place each Exquisite Blood's ability on the stack, and they will resolve one after the other.

An opponent loses life.

Exquisite Blood #1's ability triggers.
Exquisite Blood #2's ability triggers.

You place Exquisite Blood #1's ability and Exquisite Blood #2's ability on the stack in the order of your choice. (Here, we'll place #1 on the stack first.)
Exquisite Blood #2's ability resolves,

You gain as much life as your opponent lost.

Exquisite Blood #1's ability resolves,

You gain as much life as your opponent lost.

The converse is true as well. If multiple instances of a event occur simultaneously, an ability can trigger more than once.
For example, a Dingus Egg's ability will trigger once for each land sent to a graveyard, even if multiple lands are sent there at the same time (e.g. from Armageddon). For each time the ability was triggered, it will go on the stack, and it will resolve separately.

That can't happen with Heart-Piercer Manticore, however.

"When Heart-Piercer Manticore enters the battlefield" means "When this object enters the battlefield".

201.4. Text that refers to the object it’s on by name means just that particular object and not any other objects with that name, regardless of any name changes caused by game effects.

That means that a Heart-Piercer Manticore's ability won't trigger when a different Heart-Piercer Manticore enters the battlefield. For that to happen, the ability would have been phrased "Whenever a creature named Heart-Piercer Manticore enters the battlefield".
"When you do" means "When you sacrifice another creature to the first part of this ability". Other sacrifices, including sacrifices to another Heart-Piercer Manticore, do not trigger this ability.

603.12. A resolving spell or ability may allow a player to take an action and create a triggered ability that triggers “when [a player] [does or doesn’t]” take that action. These reflexive triggered abilities follow the rules for delayed triggered abilities (see rule 603.7), except that they’re checked immediately after being created and trigger based on whether the trigger event occurred earlier during the resolution of the spell or ability that created them.
Example: Heart-Piercer Manticore has an ability that reads “When Heart-Piercer Manticore enters the battlefield, you may sacrifice another creature. When you do, Heart-Piercer Manticore deals damage equal to that creature’s power to target creature or player.” The reflexive triggered ability triggers only when you sacrifice another creature due to the original triggered ability, and not if you sacrifice a creature for any other reason.

No matter how many Heart-Piercer Manticore there are on the battlefield, the following happens when one enters the battlefield:

Heart-Piecer Manticore enters the battlefield.

This HPM's ability triggers.

You place this HPM's first ability on the stack.
The ability resolves.

You may sacrifice a creature other than this HPM. If you don't, nothing further happens. Let's say you do.

The reflexive triggered ability triggers.

You place the reflexive triggered ability on the stack.
The ability resolves.

This HPM deals damage equal to the sacrificed creature's power to the targeted creature or player.


text:
Getting Carcassonne expansions 7 and 8
I have so far purchased all major expansions except expansions 7 (Catapult) and 8 (Bazaar), which I have not found anywhere (in any language).
Is the reason I can't find them because they are out of print?

I'm voting to close this question because shopping questions are off-topic

Seems to me like a good enough question, since I can't find these expansions anywhere. It's not "shopping", I just can't find them.

@BobMorane I’m not sure I see the distinction. You’re looking for where to buy them, yes? That seems like a shopping question, since the only answer I can imagine is “Retailer X has copies of it.”

I've edited the question into something slightly different, but 1) it makes it into an allowed question, 2) it's still answered by the existing answer, and 3) it provides useful information (if not to the OP, then future readers). [The OP should feel free to revert the change, of course, but that will cause the question to be closed.]

At the moment (Feb 2018), the publisher lists the expansion 7 (Catapult) as not available anymore. So your option would be to find this 2nd hand.
Expansion 8 is available at the publisher's shop.


text:
Riddleform and Hadana's Climb
I have the card Hadana's Climb and Riddleform in my deck, if I add the +1/+1 counter on Riddleform while it's on it's creature form from my Hadana's Climb will it stay there until the next turn that my Riddleform changes or will the +1/+1 counter disappear after then end of turn?

Yes, the counter will remain.
From the Comprehensive Rules:

121.1. A counter is a marker placed on an object or player that modifies its characteristics and/or interacts with a rule, ability, or effect. Counters are not objects and have no characteristics. Notably, a counter is not a token, and a token is not a counter. Counters with the same name or description are interchangeable.

You can put a counter on any object on the battlefield, as long as that object is a valid target when the ability/spell that puts a counter on it resolves. You can only put a +1/+1 counter on Riddleform using Hadana's Climb's ability if Riddleform is a creature, but any +1/+1 counters already on it when it stops being a creature will remain. It's worth noting that, since +1/+1 counters only have an effect on creatures, they'll essentially do nothing while Riddleform is an enchantment.

Yes, your Riddleform will keep the +1/+1 counters on it.
Permanents don't generally care what counters are on them unless they have and effect that says they should care. So even when your Riddleform turns back into an an enchantment it will still have it's +1/+1 counters on it (even though those counters won't do anything).
One special case to note is that your Hadana's Climb can only place +1/+1 counters on creatures. So even if your Riddleform has already received a counter or two, you will not be able to place additional counters on it with Hadana's Climb (and then cause the transform) if it is not currently a creature.


text:
Does Seedborn Muse untap Time Vault
Time Vault has the following ability:

Time Vault doesn't untap during your untap step.

Is Seedborn Muse able to untap Time Vault?

Compare "Time Vault doesn't untap during your untap step." and "Untap all permanents you control during each other player's untap step."

Yes.
Time Vault only prevents itself from being untapped during its controller's untap step. It doesn't hinder attempts to untap it at any other time.
There's a ruling about this on Seedborn Muse:

Other effects can prevent a permanent from untapping during an untap step. You do need to look carefully, however, as many effects say that the permanent does not untap during its controller’s untap step, and this card’s ability occurs during other players’ untap steps. If a card does say this, then Seedborn Muse can untap it. But some other abilities are not written this way and can still prevent a card from untapping.

Trivia: Seedborn Muse's ability isn't a triggered ability. It can't be, because noone gets priority during the untap step. (Abilities that trigger during the untap step would get added to the stack in the upkeep step.) Instead, it's a static ability that creates a continuous effect that modifies the rules.

Thank you. And yes, that is more accurate. All static abilities create continuous effects, and some continuous effects change the rules.

I don't know if relevant cards exist to ask this about... but does Time Vault's "doesn't untap" ability only affect the normal game rule for untapping during your untap step, or does it prevent other effects from untapping it during your untap step? So if Seedborn Muse instead said "untap all permanents you control during each player's untap step", would you untap Time Vault during your own untap step?

@GendoIkari,Re "does it prevent other effects from untapping it during your untap step?", Effects can't untap during the untap step. That's why Seedborn Muse modifies the rules instead. And yes, Time Vault prevents the rules from untapping it during the untap step, no matter what the rules currently are. The ruling from Seedborn Muse says as much. ("Other effects can prevent a permanent from untapping during an untap step.")


text:
Why is the card Earthcraft banned in legacy?
A similar card called Cryptolith Rite never did anything in legacy why is Earthcraft banned. Now I do understand you can tap summoning sick critters to the Earthcraft, but it can only untap basic lands so it cannot give you rainbow mana as the rites do, I do think they are comparable in power level, I really cannot understand that ban.

Is there stuff that triggers off a land untapping or tapping? At the very least a number of Auras that double and even triple the output of a land, which Earthcraft would allow to use repeatedly. But I think you're severly underestimating the potential of being able to tap "sick" creature for mana, especially when that mana could be used to create more creature.

It is an infinite combo with Squirrel Nest.
Even though this probably is the main reason why Earthcraft remains banned, it isn't the reason why it was originally banned. To clear up the confusion, we need to take a look at the history of Earthcraft bannings:

1999
March
Standard: Dream Halls, Earthcraft, Fluctuator, Lotus Petal, Recurring Nightmare, and Time Spiral are banned. Memory Jar is banned retroactively in mid March.
...
September
Extended: Dream Halls, Earthcraft, Lotus Petal, Mind Over Matter, and Yawgmoth's Will are banned.
...
2003
March
Vintage: Berserk, Hurkyl's Recall, and Recall are unrestricted.
Earthcraft and Entomb are restricted.
Legacy: Berserk, Hurkyl's Recall, and Recall are unbanned.
Earthcraft and Entomb are banned.
...
2004
September
Vintage: Braingeyser, Doomsday, Earthcraft, and Fork are unrestricted.

From: https://mtg.gamepedia.com/Banned_and_restricted_cards/Timeline
One of the reasons why Earthcraft is so broken (not in Legacy, but in Standard), is it was used to create infinite tokens with Wild Growth and Sacred Mesa. Wizards tried to fix all the fast combo decks with one go in the B/R announcement in March 1999.
Mark Rosewater posted this article on February of 2003. There is a explanation how Earthcraft was originally designed:

Earthcraft (banned in Extended) – This card started as a simple idea. Ley Druid was an interesting green creature. How about an enchantment that gives the Ley Druid ability to all your creatures? The original card looked like this:
Earthcraft
Enchantment
Each creature you control gains “: Untap target basic land.”
At first glance, this might seem like the same card, but there is one key difference. The original version text spliced the ability onto creatures. This is important because it prevented endless loops since new creatures that were created would have "summoning sickness" and thus couldn’t be used to untap more lands to play additional creatures. (A quick aside – the term "summoning sickness" is no longer in the rules, but there is no new term to describe what "summoning sickness" used to mean and I refuse to use the term "doesn’t have haste" or "has been under your control since the beginning of your most recent turn" or whatever, so I have rebelliously used the term "summoning sickness." So there!)
Why the change? Well, I happen to dig up the design notes from our database and discovered the culprit: JLM. (JLM, by the way, is Joel L. Mick, who at different times used to be Magic Lead Designer and Magic Brand Manager. The cards Jalum Tome and Jalum Grifter are both named after him. He was also the model for the art of Jalum Grifter. At the time of this note, he was Magic Lead Designer.)
3.05 JLM Stop the needless text splicing. Word as “Tap an untapped creature you control: Untap target land.”
3.07 MR We should examine whether or not this needs to only affect basic lands.
I prefer basic lands.
I think Joel’s wording is more complicated.
The last two notes weren’t signed but were by either Bill Rose, Mike Elliott, William Jockusch, or Henry Stern. As you can see, while I’m not responsible for the de-splicing of the card, if left to my own devices you might see Vintage players using this card to untap Tolarian Academy or Gaea's Cradle.

Earthcraft is considered a broken card, even though it's not even close in power level as some of the other cards in the banlist. Unbanning probably won't change anything in the Legacy format, but it could make decks like Enchantress and Elves more powerful.

but you still have to attack before you win also it t is a two-card combo with a 2 mana and 3 mana enchantments, hardly the fastest combo deck in the format.

You're correct. This ban has also historic reasons, and I believe Wizards just weren't able to revise the ban. Earthcraft is one of the cards in the ban list, that Wizards might unban at some point in time.

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text:
Show and Tell and permanents that target other permanents
Say I cast Show and Tell. I put down Angel of Despair and my opponent puts down Crystalline Sliver. "When Angel of Despair enters the battlefield, [you] destroy target permanent". Crystalline Sliver gives all slivers shroud so can I destroy slivers with Angel of Despair's ability?
If Crystalline Sliver entered the battlefield first I couldn't but if it entered the battlefield second, after Angel of Despair did, I could. But what if they enter into the field at the same time?
Also, in this same vein, what if my opponent plays Gilded Drake? Can my opponent target my Angel of Despair with his Gilded Drake?

can I destroy slivers with Angel of Despair's ability?

No.
The order[1] doesn't matter. Triggered abilities are only placed on the stack when a player would get priority, which is only after Show and Tell has finished resolving. By that time, every player's cards have already been placed on the battlefield, so the Angel's ability is unable to target Slivers.

Can my opponent target my Angel of Despair with his Gilded Drake?

Yes.
When the abilities are placed on the stack once a player would get priority (when Show and Tell finishes resolving), they are placed on the stack in APNAP order. The following happens afterwards:

As the Active Player, you place your triggered abilities on the stack first. You choose target for the Angel's ability at this point.
Your opponent now gets a chance to place his triggered abilities on the stack. He chooses a target for his Drake's ability at this point.
Drake's ability resolves.
Angel's ability resolves.

The choices is made in APNAP order, but the card are are placed on the battlefield simultaneously. (There's a ruling on Show and Tell confirming this.)

One interesting finesse to this answer: because of the way exchange effects work, if you manage to play Show and Tell on your opponent's turn and they put in Gilded Drake to your Angel of Despair, you can blow up the Drake and keep your Angel.

(Briefly: Drake's ability will go on the stack first, since its controller is the active player; Angel's ability will thus resolve first, destroying Gilded Drake.  Since Gilded Drake no longer exists, an exchange can't be made (section 701.8a of the comprehensive rules) and so Nothing Happens.)


text:
Can one use a Wordly Tutor to fetch Nylea, God of the Hunt
Worldly Tutor searches your library for a creature card. So could I find Nylea, God of the Hunt with it since Nylea is an Enchantment Creature?

Yes.
Nylea is always a Creature card (among other things) in your library.
It doesn't matter that Nylea isn't just a Creature.

Ruling:

The type-changing ability that can make the God not be a creature functions only on the battlefield. It's always a creature card in other zones, regardless of your devotion to its color.

If the ability was a characteristic-defining ability, it would function in all zones.

604.3. Some static abilities are characteristic-defining abilities. A characteristic-defining ability conveys information about an object’s characteristics that would normally be found elsewhere on that object (such as in its mana cost, type line, or power/toughness box). Characteristic-defining abilities function in all zones. They also function outside the game.

But it's not a characteristic-defining ability because it fails criteria 5.

604.3a A static ability is a characteristic-defining ability if it meets the following criteria: (1) It defines an object’s colors, subtypes, power, or toughness; (2) it is printed on the card it affects, it was granted to the token it affects by the effect that created the token, or it was acquired by the object it affects as the result of a copy effect or text-changing effect; (3) it does not directly affect the characteristics of any other objects; (4) it is not an ability that an object grants to itself; and (5) it does not set the values of such characteristics only if certain conditions are met.


text:
Diplomatic Immunity, card's self abilities and equipments
I have card Diplomatic Immunity (from Mercadian Masques)

It says that both the enchantment itself and the creature enchanted can't be target of spells or abilities (called shroud now, it seems).

If I enchant a creature that have, for e.g., R: Gets +1/+0 until end of turn, will this card block the creature's self-ability also?
Considering any Equipment (which have a cost for equipping on something), does that card block the equip also? If yes, if I equip first then enchant, will the equipment be removed or will it stay shrouded also?

Target is a special word in Magic; if a spell or ability targets, it will say "target" in the rules text. The only time it doesn't is if it's hidden away inside a keyword - in which case the reminder text for the keyword (if present) will say "target". (Or I suppose a card subtype - Auras target.)
In the first case, the creature doesn't target itself, so that's fine, the ability still works.
In the second case, the Equip ability does target, as you can see from its reminder text, for example:

Equip {3} ({3}: Attach to target creature you control. Equip only as a sorcery.)

It says target, so you can't equip your creature. But it only targets as you're activating the ability, so if the equipment is already attached to the creature when you enchant it with Diplomatic Immunity, it'll stay there. You might be interested in this rules summary for Equipment, which in fact mentions these very things:

The equip ability can't target a Gigapede, because it can't be the target of spells and abilities. There's no real way around this, even though being untargetable wouldn't cause the equipment to fall off. If the Warhammer is equipping a Glimmering Angel, making the Angel untargetable won't make the Warhammer fall off.

Thanks for the explanation and for sharing the rules for equipment. I actually stopped playing when Mirrodin was released and I'm just getting back on the game now, so I need to read more about equips (and planewalker stuff).


text:
Does "+X +X until end of turn." effects remain on creatures in the graveyard and/or exiled until end of turn?
If I use Culling the Weak to sacrifice 4 creatures for 16 black mana, then use 15 of that mana on Whispering Shade to make it stronger, can I then sacrifice them to get 5 mana for Living Death to bring all my creatures back with Whispering Shade  being a 16/16?

No. Creatures only exist on the battlfield. When Whispering Shade is in the graveyard, it is a creature card. When Living Death returns the card to the battlefield it is a new object with no knowledge of its previous existance.

What is "them" in "can I then sacrifice them"?

I think 'them' refers to his Whispering Shade. Sacrificing 5 creatures with Culling the Weak would be problematic, as you need to cast it 5 times.

There seems to be a hefty amount of misunderstanding of the game rules in this question.

First of all, with a single Culling the Weak, you can only sacrifice a single creature, not as many as you like. If you could use it multiple times, it would explicitly say so in the text. (Be sure to check the text in the Oracle rather than the text on the physical card.) You can use Living Shade's ability as often as you like, but there is a difference between a one-shot spell effect and an activated ability.
Secondly, once you cast CtW, you cannot cast another spell (Living Death) and then continue sacrificing to CtW, because CtW has resolved, is in the graveyard, and its effect is over.
Thirdly, if you activate Living Shade's ability to make it stronger, then sacrifice it, then bring it back into play from the graveyard, it will be a completely new Living Shade with no "memory" of its previous existence, and thus will be 1/1.

+1 Spot on, it even say's you cannot sacrifice more than one creature in the rulings http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=6085


text:
Do creature effects trigger every time they move base?
Do creature effects trigger every time they move base, or just the first time they enter play?
For example, if I play Invader, gain 1 VP, then play Invasion and move it to a second base, do I gain another VP?

I just stated an example effect in my question.

No, Invader grants a victory point when it's played, not when it's moved.

Play: You play a card
  when it’s one of the
  free cards you get in
  step 2, or any time an
  ability specifically says
  that you’re playing it. A
  card’s ability happens
  when you play it. When
  cards are moved, placed,
  or returned, they’re not
  being played, and their
  abilities don’t happen.
Move: This lets you
  move a card from one
  location to another.
  Moving a card does
  not count as playing it.
  Minion abilities do not
  happen when you
  move a card.


text:
Revolution! with Anarchy expansion: when does the game end?
Normally, Revolution! ends when all influence squares are filled. The Anarchy expansion adds Garden, Asylum, and Jail --- do these also need to get filled for the game to end? If so, how do you avoid a mad frenzy over jail and asylum in the end?

I didn't find a copy of the rules, but the expansion seems to consist of a board that replaces certain districts like The Palace did. I don't see why the end-of-game would be any different than without the expansion.
As for end-of-game frenzy, there's always a lot of cube manipulations at the end of the game. The person in the lead tries to end the game, while the others are vying to move cubes instead of adding them (or they are trying to get the resources to win the roles that would allow them to do so). Nothing new here.


text:
How does stealing a creature's text box work with copies?
Phoebe, Head of S.N.E.A.K. has an ability which says:

{2}{U}{B}: Phoebe permanently steals target creature’s text box. (That creature loses all rules text, flavor text, and watermarks. This creature gains them.)

What happens when this is used on a Clone (or another creature) that is copying something, such as a Charging Badger? Does she gain the Badger's or the Clone's text box? (Does she gain both?)

Phoebe will steal the (cloned) Badger's text box.
Clone states:

You may have Clone enter the battlefield as a copy of any creature on the battlefield.

According to rule 706.2, one of the "Copiable values" is, in fact, Rules Text.

706.2. When copying an object, the copy acquires the copiable values of the original object’s characteristics and, for an object on the stack, choices made when casting or activating it (mode, targets, the value of X, whether it was kicked, how it will affect multiple targets, and so on). The “copiable values” are the values derived from the text printed on the object (that text being name, mana cost, color indicator, card type, subtype, supertype, rules text, power, toughness, and/or loyalty), as modified by other copy effects, by its face-down status, and by “as . . . enters the battlefield” and “as . . . is turned face up” abilities that set power and toughness (and may also set additional characteristics). Other effects (including type-changing and text-changing effects), status, and counters are not copied.

So, that means that Clone's text box will be the same as whatever creature it's copying1 (in fact, Clone will be the creature it's copying), which in turn will be stolen by Phoebe's ability.
If the copy has added abilitites (such as Dack's Duplicate), Phoebe will steal those abilities as well, so for the Duplicate, Phoebe would also gain Haste and Dethrone.

1: Except for flavour text and watermark, naturally2
2: Unless it's a silver-bordered game, in which case it will include those after all. Kudos to @murgatroid99 for pointing that out.

This post from Mark Rosewater seems to imply that in silver-bordered play, Clone copies additional attributes that only silver-bordered cards care about, which would include flavor text and watermark.

Further clarification: the situation in question is by definition a silver-bordered game because it involves Phoebe, Head of S.N.E.A.K.

all_licenses: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


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How to build / ideas for a multiplayer lifegain control deck?
I'm more of the dueler type, but sometimes I play multiplayer with my friends. At this point my decks are just not viable.
I want to build a multiplayer deck for this purpose. When I check online multiplayer decklists I see a lot of 1 or 2 singles of the same cards in a heavely not consistent deck rather then lots of 4 of making a solid and constant deck. Is there a reason for that?
Also, I would like to build a life-gain/control deck. is it possible for a fun deck to play in multiplayer? If yes, I would be glad to have some ideas from experienced multiplayer players.
Thanks in advance!

Extort. In multiplayer 1 manna can net you as much life as there are opponents. It is brutal in multiplayer. I built a great 90 card extort/anti-creature deck and when I play it in my group of 5, it always ends up feeling like a game of Arch enemy.

@Pow-Ian Ditto, Gray Merchant.

If you want to start your own research: http://gatherer.wizards.com/Pages/Search/Default.aspx?page=0&sort=cmc+&text=%20%5B%22each%20opponent%22%5D

http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=210235 Is great in a multiplayer deck. I have 4 of those in mine, and it will give loads and loads of lifegain. My multiplayer deck is mono black, with loads of all players sacrefice creatures and then Exsanguinate.

There are a couple main reasons you might see a lot of multiplayer decks with 1 or 2 of each card.
First and foremost, multiplayer is a pretty casual format, so people are playing with the cards they own, and trying not to spend all their money. They probably only have 1 or 2 of a lot of cards, so they're just building the deck they can build.
Along with that, casual games tend to be about fun, not just winning, and a lot of people do like the excitement and variety of having a lot of different cards. There's something to be said for getting to cast a bunch of different spells, even if they're not quite as good as the 4-ofs you might put in the deck if you wanted to perfect it. People obviously really like this; Commander is getting pretty popular, and the entire format is built around the idea of having only one of each card.
As for your specific deck idea, sure, it's possible!
First of all, remember, lifegain is in general a weaker mechanic than it seems at first, because unless you actually deal with the things that keep making your life go down, it only buys you a little time. So you really need to make it count - find the most efficient life gain you can. This means both getting the most life you can out of it, and hopefully getting an extra benefit. Happily, extort and Gray Merchant (mentioned in the comments) do both. They gain life for each opponent, so lots of lifegain. But they also drain your opponent, and give you an extra creature. (Or in the case of Blind Obedience, slow down aggro decks.)
Depending on your constraints (and your collection) there are probably a lot more cards in that vein - try searching for "each opponent" gain life or even just "gain life equal to", and you'll find some more potential candidates.
Beyond that, it does depend on the kinds of decks your friends play. If you're surviving to the late game but still losing, maybe you just need better win conditions. If you're getting killed early before you can get your cool stuff online, maybe you need some faster removal, or in general faster answers to the kinds of things they're trying to do. The control side of your deck needs to be strong and efficient too, not just the lifegain. But it's hard to give terribly specific advice here; we don't know what kind of decks you're playing against, or what kind of cards you have at your disposal. I think about the best general advice is to look at what's killing you and figure out ways to address it efficiently.

There's another reason why multiplayer decks have more 1 and 2 of cards - they need to be more toolboxy to play across multiple different strategies at the same time, and multiplayer games are usually best of one, not best of three, so that toolbox needs to be in the maindeck, no taking out your anti-aggro cards for game 2 when playing against control like you get in best of 3 one on one.

Life gain as a deck idea works better in multiplayer than it works one on one in a lot of ways, because there are many cards that drain each opponent of life, cards like Exsanguinate or Gray Merchant of Asphodel take life from each opponent in sometimes very large amounts and give it all to you, cards like Soul Warden and Deathgreeter get more to trigger from, as more players play more creatures, and the more creatures there are, the more that will die during a game. The extort mechanic on cards like Pontiff of Blight also lets you bleed your opponents slowly, paying a little extra for your spells to steal life.
Just gaining life though tends to have little use as Cascabel said, it's a delaying tactic more often than not, you have to make use of that life gained. Some cards can be cast with life as part of the cost, like Snuff Out or very recently Aetherflux Reservoir which has been used as a win condition competitively, and cards like Phyrexian Arena and Dark Confidant let you spend that life for card advantage. The act of gaining life itself can be made use of in some cases, by using cards like Cradle of Vitality or Archangel of Thune to strengthen creatures, or Well of Lost Dreams for draw. Having a high life total can also power cards like Serra Ascendant or even act as a win condition directly with Felidar Sovereign
The best use of lifegain though is generally to make your opponents lose more life. Cliffhaven Vampire, Defiant Bloodlord, Epicure of Blood, Sanguine Bond and Vizkopa Guildmage can all cause your opponents to lose more life, one life per gain in some cases or as much as was gained in others. Any of these effects combined with Exquisite Blood win you the game, with life loss on your opponents triggering life gain for you creating the cycle until they are all dead. Tainted Sigil can be a much more limited version of this, since it sacrifices to trigger.


text:
Destroying a Planewalker before its ability is used
Say my opponent plays a planeswalker during their first main phase.  I have a Hero's Downfall or some other effect that will kill it after it is already in play, but before they use any of its abilities.  I could respond to them using a +1 ability, but I want to kill it before that effect goes on the stack.
In most casual situations, it would basically come down to whether I say "Hero's Downfall" first, or they say "+1" first.  But I can't imagine that's how it's supposed to work.  Is there a time between when the planeswalker hits the battlefield and when they activate its abilities that they must let me respond? It seems to me that situations like this arise frequently, and they are resolved simply by who speaks up first, which is horrible for such a rules-oriented game.

possible duplicate of Casting a spell after a spell resolves?

I think the author of the question should clarify the issue of priority better: especially, to understand how MTG is not at all a "naive" game from this point of view, as it seems he believes it is. Or, at least, that's what anyone could understand, by reading the final tone of your question ...

MTG is a turn-based game. There is never a time when it matters who said what first.[CR 117.1]
After a spell resolves, the Active Player regains priority.[CR 117.3b] They can then activate one of their Planeswalker's abilities before anyone else can do anything. If you play a Planeswalker and it's not countered, you're practically guaranteed to get a free use of its loyalty ability if you use it immediately after the Planeswalker resolves.[1] The Planeswalker is effectively a very expensive Sorcery if your opponent proceeds to destroy it in response to its ability.[2]
If you pass priority[3], then you could lose your chance to use the Planeswalker's loyalty ability because you allow your opponent to cast Hero's Downfall. If you cast another spell or activate another ability, or if an ability triggers in response to the Planeswalker entering the battlefield, then you could lose your chance to use the Planeswalker's loyalty ability because your opponent could cast Hero's Downfall in response this new spell or ability.
However, if your opponent said they're casting Hero's Downfall before one of these things happen, they're playing out of turn[4].

Notes:

This doesn't apply if it's put into play, or if you somehow play it outside of your main phase or when the stack isn't empty. It also assumes that nothing triggers on it entering the battlefield.

Compare Ajani Goldmane's +1 (2 life for 4) with Sacred Nectar (4 life for 2), although his -1 is better than common Marshaling Cry's for only one extra mana.

For example, by declaring attackers. If you do so, your opponent can say "hold on" or similar (to "shorten your shortcut"), and cast Hero's Downfall.

At which point, you say "hold on" or similar, and activate the ability.

Rules:

117.1. Unless a spell or ability is instructing a player to take an action, which player can take actions at any given time is determined by a system of priority. The player with priority may cast spells, activate abilities, and take special actions.
117.3b The active player receives priority after a spell or ability (other than a mana ability) resolves.

As a matter of tactics, if the planeswalker's ability has already been activated, generally it would be better for the opponent to destroy the planeswalker at the end of the turn than in response. After all, you never know what other threat may come along that would make a better target for Hero's Downfall, right? I'm sure there's some edge case where it's better (killing it to lower devotion comes to mind, but you can still defer until that point so it still is bad to use it in response) but generally I'd not do it in response.

@corsiKa: Usually yes, though it's possible you want it removed from the battlefield anyway, such as Gideon Jura activating its +0 ability when the opponent has Lightning Greaves in play.

@VolleyJosh Exception to the first line: http://gatherer.wizards.com/pages/search/default.aspx?text=+%5Bgotcha%5D

That's no exception; those cards can't be used.

So the planeswalker can be destroyed, but the loyalty ability will still resolve, since it uses the stack and is not related to its source being destroyed. Is that correct?

@Shade, Yes. It was never in doubt that the planeswalker could be destroyed.

Now I wish there was an enchantment that read "Whenever a permanent enters the battlefield scry 0." (or some other do-nothing effect).  Because it would allow anyone to kill fresh planeswalker at instant speed before their abilities could be activated. And probably some other shenanigans as well.

@Joachim Sauer, "Whenever a planeswalker enters the battlefield under an opponent's control, ..." ;)

"There is never a time when it matters who said what first." That's not quite right. There's never a point where the game waits to see who speaks first, without anything else happening. But it certainly does matter who said what first, in the sense that saying something, then passing priority, then someone else saying something, can result in a result different from passing priority, then someone else something, then you say your thing.

@Acccumulation, Yes, doing something that's not passing priority is different than passing priority. I don't think anyone who read what I wrote thought otherwise. It's pretty obvious I'm talking of the order in which different people say things, not the order in which a single person says things.

@Acccumulation Some Un-cards also depend on what people say.

Scenario 1: Alice says "I cast shock". Bob says "I cast Giant Growth". Scenario 2: Bob says "I cast Giant Growth". Alice says "I cast shock". These two scenarios can have different results. Not because of the order in which a single person says things, but because of the order that different people say things. Of course, a full description would be longer, e.g. Scenario 1 is "Alice has priority, and casts shock, then passes priority, and Bob then gains priority and casts Giant Growth".

@Acccumulation You are mistaken. In both scenarios, the same thing happens. Alice casts her spell if she has priority, or Bob casts theirs if they have priority. It doesn't matter who talked first.

As I said, the full description would be longer. If the second is short for "Alice passes priority, Bob gains priority, Bob casts Giant Growth, Bob passes priority, Alice gains priority, Alice casts Shock", then the scenarios can have different results.

@Acccumulation No, scenarios can't have different results because of the order in which people say things. They can have different results because of other reasons, but these are irrelevant here.

Because of the way timing an priority works, your assertion that:

In most casual situations, it would basically come down to whether I
  say "Hero's Downfall" first, or they say "+1" first.

is incorrect.
The active player always has priority on their turn until they pass it. This means they always have an opportunity to cast spells and activate abilities before their opponent(s) in each of the phases of their turn.
So the only time in which you have a chance to 'respond' is if they start the stack again or they pass.

Since the active player gets priority after the planeswalker resolves, there is no time you can play an instant before they activate one of the loyalty abilites, unless they start the stack somewhere else with another instant or sorcery.

116.3b The active player receives priority after a spell or ability (other than a mana ability) resolves.
116.3c If a player has priority when he or she casts a spell, activates an ability, or takes a special action, that player receives
  priority afterward.
116.3d If a player has priority and chooses not to take any actions, that player passes. If any mana is in that player's mana pool, he or
  she announces what mana is there. Then the next player in turn order
  receives priority.
116.4. If all players pass in succession (that is, if all players pass without taking any actions in between passing), the spell or ability
  on top of the stack resolves or, if the stack is empty, the phase or
  step ends.

So here is how it breaks down:

Player A puts a planeswalker on the stack.
Noone wants to add to the stack, so it resolves and enters the battlefield as a permanent.
Because the Active player now has priority again, they have the opportunity, as a sorcery, to activate a loyalty ability of the planeswalker and they do.
Player B casts Hero's Downfall in response.
Everyone passes so Hero's downfall resolves. The planeswalker is destroyed.
The planeswalker's loyalty ability resolves because it is it's own entity once it is in the stack.

602.2a The player announces that he or she is activating the ability. If an activated ability is being activated from a hidden zone, the
  card that has that ability is revealed. That ability is created on the
  stack as an object that's not a card. It becomes the topmost object on
  the stack. It has the text of the ability that created it, and no
  other characteristics. Its controller is the player who activated the
  ability. The ability remains on the stack until it's countered, it
  resolves, or an effect moves it elsewhere.

Another way it could happen:

Player A puts a planeswalker on the stack.
Everyone passes, so it resolves and enters the battlefield as a permanent.
Player A activates the ability of Gilder Bairn.
Player B cast's Hero's Downfall.
Everyone passes.
Hero's Downfall resolves and the planeswalker is destroyed.

Because the loyalty ability of the planeswalker is not an instant, but a sorcery, they can't activate it in response to Hero's downfall and the planeswalker dies before the ability can be used.
It comes down to loyalty abilities can not be activated in response to anything because they are cast as a sorcery, not an instant.

Well, it has nothing to do with using the loyalty ability as a response, since that's not the question, but the first part of your answer is relevant.  The reason I have cause to doubt that I wouldn't have a chance is that every piece of software Wizards has published allows players to cast instants or use creature abilities during the main phase of their opponents, even when they haven't passed priority.  Could just be limits of the medium I guess.

I put the first part in there because it shows that you can't use a loyalty ability as an instant. But I agree, it is not necessary.

@Indigenuity Actually in Magic software (as in paper Magic), you can only cast spells or activate abilities during your opponent's main phase after that player has had an opportunity to do so first. Sometimes it might not be clear that the player whose turn it is gets the first shot at playing things, but it is the case.

@DavidZ Well, I've had many games where I used the Icy Manipulator to tap down an opponent's land during their first main phase on Duels of the Planeswalkers 2013. BEFORE they've done anything.  I assume this is to 'simulate' the upkeep step that is skipped.

@Indigenuity Ah, well, I don't know how DotP works, but what you're describing can't happen in actual Magic.

@Indigenuity, Duels of the Planeswalkers is a poor simulation of the game when it comes to priority. In that game, reflexes do come into play in certain situations.

Normally, when you cast the planeswalker, you have priority when it enters the battlefield.  With priority, you can activate one of it's abilities (putting that ability on the stack) before any other player can put something on the stack.  At this point, even if someone destroys your planeswalker, it's ability will still resolve.
But, planeswalker abilities are sorcery speed.  If, at the point in time the planeswalker enters the battlefield, it is not your main phase and/or the stack is not empty, you will not be able to put one of its abilities on the stack right away and other players may target it with instant speed removal before you can use one of it's abilities.  Some situations in which this could happen:

You cast the planeswalker either not as the bottom thing on the stack and/or not during one of your main phases (such as through Vedalken Orrery).

Something triggered when the planeswalker entered the battlefield, such as due to Arcbound Crusher and Mycosynth Lattice.

You try to do something else first, such as use Gilder Bairn on the planeswalker]

Another exception is if the ability requires the planeswalker to function.  If the +0 ability of Gideon Jura is used and he is targeted with Hero's Downfall in response, the ability won't do anything on resolution because Gideon is no longer on the battlefield.
Exception to some of the exceptions: if you have the emblem from Teferi, Temporal Archmage, you can use one of a planeswalker's abilities in response to someone trying to destroy it.
Exception to that exception: you will not be able to respond with a planeswalker ability to removal with Split Second such as Wipe Away.


text:
End of abilities given off by creatures
If I'm attacking with creatures that give off abilities and the other person blocks and kills the creature does its ability die off with the creature at that same moment leaving the others creatures without it.

No, because as long as those other creatures attacked in the same turn the given abilities don't go away until your turn is over even if the creature that gives off the ability dies. (Dragonlord 619/ iron giant)

huh? Is this a magic the gathering question, or a Warhammer 40k question. What do you mean by "give off abilities"? The answer would change if the ability is a static ability (creatures you control get +1/+1), or a triggered ability (whenever a creature you control is blocked).

"Give off abilities" is not clear. It helps if you use proper jargon or at least an example. I believe you are talking about continuous effects created by static abilities such as Wizened Cenn's.
Effects created by static abilities take effect the moment the object on which they reside enters the battlefield, and they end the moment that object leaves the battlefield.
For example, say you have Wizened Cenn and Amrou Seekers on the battlefield, and your opponent deals 2 damage to each of your creature. This marks two damage on both your creatures. This kills off your Cenn, which reverts your Seekers to 2/2, which kills them off too.

Since he mentioned attacking with these creatures, I assume that he's wondering about combat damage, specifically how much damage is creatures will deal. Might want to mention that since all combat damage is simultaneous, he will deal the increased amount.


text:
What happens to a spell if an oppenent runs out of mana while casting it?
My friend and I were playing Magic the Gathering when he tried to summon Ghor Clan Rampager. He used all his mana to cast him, but in response I played Twiddle and tapped one of his lands. What would happen to his creature?

The best time to twiddle a land if you want to stop someone from using it, is at the end of their upkeep when they pass priority. This way the mana they could produce by tapping in response is gone because it was at the end of a phase.

The answers make it clear that you cannot respond before the mana is tapped. But let's change the universe a little so you can, for just a moment. Why couldn't he respond to your twiddle by tapping his land?

What happens to a spell if an oppenent runs out of mana while casting it?

That's impossible. There is no chance to spend mana between the point where one starts casting a spell and the point where one pays for it.[1]

but in response I played Twiddle and tapped one of his lands.

"In response to" means "after it has been cast but before it resolves". When Ghor Clan Rampager is cast, the lands have already been tapped and the mana has already been produced.[1]
(Or did you mean in response to activating the land's ability? One cannot do anything in response to activating a mana source as it does not use the stack.)
You would have to cast Twiddle before he casts Ghor Clan Rampager (which means before he even mentions he's going to cast it), but then he could just tap the land for mana in response to you casting Twiddle, so it would have no effect.

Notes:

The steps to casting a spell or activating an ability are:

601.2a) Place card on stack.
601.2b-d) Make choices, including targets.
601.2e) Check if spell can legally be cast.
601.2f) Determine total cost.
601.2g) Activate mana abilities.
601.2h) Pay the previously determined cost.

To be more precise, tapping a land is an action that does not use the stack, and thus cannot be responded or prevented by a spell (not even a spell with Split second) cast at that time (as opposed to casting the spell at an earlier time).

@Circeus: To expand on your split second example (since I at first got it wrong), split second has an explicit exemption for mana abilities.

(@Circeus's comment was incorporated into the answer yesterday.)

I said it's impossible, but it is possible in very weird circumstances. See tengfred's answer for details about that odd situation.

The answer by @ikegami correctly describes the specific situation in this question. For the more general question (as stated in the headline), the answer is that if a player finds he is unable to pay any costs (e.g. because he miscalculated the mana available), the game will be restored to the point before the spell casting was started, see comprehensive rule 601.2.

The biggest example for not having enough mana during the casting of a spell is usually Selvala, Explorer Returned, since you could have anywhere between 0 and 4 (in commander/2hg) mana from her ability but you don't know which until she's been activated.

Tapping mana doesn't go on the stack, so therefore you cannot react to it and tap his land before he creates mana off it. The casting cost of his spell is determined at the time of casting, and before putting the spell on the stack (casting) he has to pay the cost.
He has to tap his lands (for mana), something you cannot react to, then cast his spell. But the mana is already in his pool.
What probably happened (I see it a lot). He put his creature on the battlefield and he wanted to tap his lands, but you wanted to react to it. It should be the other way around, first tap for mana, then cast the card.
If somehow you got priority before he taps his lands (for example as a reaction on another spell), you can tap his lands with Twiddle. But even then, when you target his land with your spell, he can react to it and tap it himself (for mana).

the proper steps for casting a spell, are to reveal it, pay its costs and then put it onto the stack. you can tap your mana first if you want, but you dont HAVE to. from the moment he reveals his spell, his opponent cannot respond until after it is on the stack, giving him plenty of time to activate his lands etc as required.


text:
If I target my own Rancor with a Terastodon will the effect still take place and give me a 3/3 elephant token?
If I target my own Rancor with a Terastodon will the effect still take place and give me a 3/3 elephant token?
I ask this question because there is a ruling on Terastodon that says:

If a targeted permanent has indestructible or regenerates, its controller won't get an Elephant token for it. Similarly, if the targeted permanent is destroyed but a replacement effect moves it to a different zone instead of its owner's graveyard, its controller won't get an Elephant token for it.

So I suppose the question is, does the effect of Rancor returning to its controller's hand count as a replacement effect?

Yes, you will still get the 3/3 Elephant token when you destroy your Rancor with your Terastodon.
Rancor's ability is not a replacement effect, it is a triggered ability. The ability triggers and moves Rancor to your hand after it has already moved to the graveyard. The relevant rule is 112.3c:

Triggered abilities have a trigger condition and an effect. They are written as "[Trigger condition], [effect]," and include (and usually begin with) the word "when," "whenever," or "at." Whenever the trigger event occurs, the ability is put on the stack the next time a player would receive priority and stays there until it's countered, it resolves, or it otherwise leaves the stack. See rule 603, "Handling Triggered Abilities."

So, when your Terastodon's ability resolves targeting Rancor, a few things happen. First, your Rancor is destroyed (and moved to the graveyard) and you get an Elephant token. Then, when the ability has finished resolving, you get priority and Rancor's third ability is put on the stack. Finally, Rancor's ability resolves and it moves from the graveyard to your hand.

Terastodon gives you an elephant "for each permanent put into a graveyard this way".
If a permanent regenerates, it doesn't get destroyed, so it doesn't go to the graveyard, so it doesn't result in an elephant.

701.12a [...] “Regenerate [permanent]” means “The next time [permanent] would be destroyed this turn, instead remove all damage marked on it and tap it. If it’s an attacking or blocking creature, remove it from combat.”

Rancor must go to the graveyard before its ability triggers to eventually send Rancor back to your hand, so you still get the elephant.


text:
Angel's Grace and Phyrexian Unlife
I am at -10 life from Ad Nauseam but I don't lose due to Phyrexian Unlife. If my opponent attacks me with all their creatures (for infect-> poison counters) and I use Angel's Grace what happens to my life total? I know it doesn't go back to 1 but do I get poison counters or just one poison or does nothing happens?
Similarly,
If my health is already below zero and I don't have Phyrexian Unlife if my opponent keeps attacking on the turn I'm still using Angel Grace what happens?
thanks

Related (essentially a duplicate of your second question): http://boardgames.stackexchange.com/questions/6987/can-angels-grace-set-your-life-total-to-1-when-you-have-negative-life?rq=1

In the first scenario,
Your opponent's creatures deal damage to you in the form of poison counters.[CR 702.89b] This damage does not reduce your life total, so it's not affected by Angel's Grace. Even if you now have ten or more poison counters, you do not lose at this time because of Angel's Grace.
Eventually, your turn ends and the continuous effect Angel's Grace's created to keep you alive ends. Specifically, this happens in the Cleanup Step[CR 514.2]. At this point, state-based actions are checked and you lose if you have ten or more poison counters.[CR 514.3, 704.5c]

702.89b Damage dealt to a player by a source with infect doesn’t cause that player to lose life. Rather, it causes the player to get that many poison counters.

In the second scenario,
Everyone's life totals are checked whenever someone is about to get priority (when someone gets to cast a spell or activate an ability except when instructed by an effect)[CR 116.5].
If your health is below zero, and you don't have Phyrexian Unlife to keep you alive, then you've already lost. As soon as Ad Nauseam finished resolving, before anyone could have done anything else and before the attackers could deal their damage, state-based actions were performed[CR 601.2h] and you lost the game for having having non-positive life.[CR 704.5a]

601.2h Once the steps described in 601.2a–g are completed, the spell becomes cast. Any abilities that trigger when a spell is cast or put onto the stack trigger at this time. If the spell’s controller had priority before casting it, he or she gets priority.
116.5. Each time a player would get priority, the game first performs all applicable state-based actions as a single event [...]

Do note that Angel's Grace cannot raise your life total. As stated in a ruling, "If your life total goes below 1, being dealt damage will not increase it back up to 1."

I won't answer your second question since it's essentially the same question as the question I linked in my comment above.
As for the answer to your first question, the second ability of Phyrexian Unlife is a replacement effect. Instead of taking damage, you gain poison counters. Angel's Grace only checks if damage would reduce your life total to less than one, but it doesn't replace the damage, nor does it care about poison counters. Therefore you would still gain your poison counters.
However, Angel's Grace prevents you from losing the game. So what would happen is that you would keep the poison counters. If you received ten or more of them, unless you had some way to rid yourself of the poison counters, at the beginning of the next player's upkeep, when you receive priority, comprehensive rule 104.3d kicks in:

104.3d If a player has ten or more poison counters, he or she loses the game the next time a player would receive priority. (This is a state-based action. See rule 704.)

You actually lose in your own cleanup, not the next player's upkeep.

Phyrexian Unlife is not actually a replacement effect. It's subject to CR 609.4 rather than CR 614. Or maybe you meant Infect is a replacement effect, but Infect isn't a replacement effect either. It's not an effect at all. It's an ability whose presence is checked by the rules governing dealing damage. There's nothing being replaced, as you can see by reading [CR 119.3]. If it was a replacement effect, you would be able to apply Angel's Grace's replacement before Infect. But you can't because neither Phyrexian Unlife nor Infect create a replacement effect.

Re "Instead of taking damage, you gain poison counters.", You still take damage even if the source has Infect. It can prevented, just like any other damage, for example. The damage doesn't cause life loss, but it's still damage. "You take damage that causes you to gain poison counters."

Instead of that, try running form of the Dragon instead. Because combat damage is dealt at the same time (unless a creature has first strike/double strike) you're life will just reset to five at the end of the turn. I run that combo in a lot of my white decks and it's always been extremely effective.

Welcome to the site! This is a Q&A site, not a discussion forum (see the [tour]) so it's expected that you answer the question here. And... I'm not sure what you're trying to suggest here. Form of the Dragon definitely doesn't let you go to negative life. You'll lose immediately when you drop to zero or below, and you'll never get to the end of your turn where your life would become 5.


text:
If Gray Merchant dies and is revived by something like Undying Evil, does it repeat it's loss of life when it is revived?
If Gray Merchant dies and is revived by something like Undying Evil, does it repeat it's loss of life when it is revived?
Also, if you used a card like Twilight's Call and he was revived with a bunch of other black creatures would the other revived black creatures count towards your devotion?
Thanks.

Question 1. Yes, he enters the battle field and thus his ability triggers.
Question 2: Yes, you use the devotion at the time the spell resolves.
A ruling on Gray merchant of asphodel has this:

If an activated ability or triggered ability has an effect that
  depends on your devotion to a color, you count the number of mana
  symbols of that color among the mana costs of permanents you control
  as the ability resolves. The permanent with that ability will be
  counted if it’s still on the battlefield at that time.


text:
Can you revive the creature you sacrificed with Hell's Caretaker?
Can you revive the creature you sacrificed with Hell's Caretaker?
Doing so to re-trigger "enters the battlefield" effects.

If you have more than 1 other creature, you can swap them in and out of the GY, though. You can even go infinite using 2x Deceiver Exarch.

No
The steps to casting a spell or activating an ability are:

601.2a) Place card or ability on stack.
601.2b-d) Make choices, including targets.
601.2e) Determine total cost.
601.2f) Activate mana abilities.
601.2g) Pay the previously determined cost.

The sacrificed creature is only moved to the graveyard in step 5, but you need to pick a card in the graveyard in step 2.

No.
You have to choose a creature to 'target' at the time you activate the ability (Rule 601.2c). At this point in the activating process, you have not payed the cost to active the ability(rule 601.2g), so the creature you would sacrifice is not in the graveyard and is not a valid target.

Yes. THis is possible. You can also use cards in your hand

Add more thorough documentation, correct grammar, punctuation, etc.


text:
Does ion damage penetrate shields?
In X-Wing, there are several ships (such as the Y-Wing) which use ion canons.
The description says:

If this attack hits the target ship, the ship suffers 1 damage and
  receives 1 ion token. Then cancel all dice results.

Assuming the target ship has shields is the damage dealt to the target ship's shields or it's hull?

No, Ion Damage is handled as normal, plus an Ion token
This is addressed in the core rules on page 16 under the heading "Suffering Damage":

When a ship suffers damage or critical damage, it suffers them one at a time following these steps. ...
  1. Reduce Shields: If there are any shield tokens remaining on the ship's card, remove one of the tokens and skip Step 2. ...

(Emphasis theirs)
The rules for receiving damage are separate from the rules for dealing damage, so unless the card specifically states that it bypasses shields, the targeted ship would receive the 1 point of damage following the normal rules.


text:
Living Lands versus Living Terrain
If you have Living Lands on the battlefield, making all of your Forests 1/1 creatures, and you then enchant one of those Forests with Living Terrain, does the enchanted land become a 1/1, a 5/6, or a 6/7?

The abilities of these cards create continuous effects, so we're interested in [CR 613], "Interaction of Continuous Effects".

613.1. The values of an object’s characteristics are determined by starting with the actual object. For a card, that means the values of the characteristics printed on that card. For a token or a copy of a spell or card, that means the values of the characteristics defined by the effect that created it. Then all applicable continuous effects are applied in a series of layers in the following order:

613.1d Layer 4: Type-changing effects are applied. These include effects that change an object’s card type, subtype, and/or supertype.

613.1e Layer 5: Color-changing effects are applied.

613.1g Layer 7: Power- and/or toughness-changing effects are applied.

613.2. Within layers 1–6, apply effects from characteristic-defining abilities first (see rule 604.3), then all other effects in timestamp order (see rule 613.6). Note that dependency may alter the order in which effects are applied within a layer. (See rule 613.7.)

613.3. Within layer 7, apply effects in a series of sublayers in the order described below. Within each sublayer, apply effects in timestamp order. (See rule 613.6.) Note that dependency may alter the order in which effects are applied within a sublayer. (See rule 613.7.)

613.3b Layer 7b: Effects that set power and/or toughness to a specific number or value are applied.

613.5. If an effect should be applied in different layers and/or sublayers, the parts of the effect each apply in their appropriate ones. [...]

The timestamp order of effects is the order in which they were created.

If Living Lands entered the 'field before Living Terrain (as in your scenario),

Layer 4, It becomes a Forest Land Creature, then it becomes a Treefolk Forest Land Creature.
Layer 5, Its color changes to green.
Layer 7b, Its P/T is set to 1/1, then its P/T is set to 5/6.

So it's a 5/6 green Treefolk Forest Land Creature.

If Living Terrain entered the 'field before Living Lands,

Layer 4, It becomes a Treefolk Forest Land Creature, then it becomes a Treefolk Forest Land Creature.[1]
Layer 5, Its color changes to green.
Layer 7b, Its P/T is set to 5/6, then its P/T is set to 1/1.

So it's a 1/1 green Treefolk Forest Land Creature.

And the tie breaker,

613.6g If two or more objects would receive a timestamp simultaneously, such as by entering a zone simultaneously or becoming attached simultaneously, the active player determines their timestamp order at that time.

It gets to keep its Treefolk subtype because its current (new) types support it.[CR 205.1].

Note that an effect giving +1/+1 is applied in 7c, so it would work even if it's timestamp was earlier than Living Lands and/or Living Terrain.

Confirmed the part I wasn't sure about.

No problem. If this answer satisfies you, please check the mark next to it. Welcome to our site :)


text:
Does a -1/-1 effect from a static ability cause a creature to die before it can do anything, upon entering the battlefield?
My friend has played Engineered Plague, naming Elf. Is the Elvish Hexhunter of any use here? Imagine it has haste via Concordant Crossroads.

Your elf can't do anything. It becomes a 0/0 just after it enters the battlefield, and pretty much immediately goes to the graveyard. There's no opportunity to activate the ability before it dies. This has to do with state-based actions, and the fact that they're checked before you get priority:

704.3. Whenever a player would get priority (see rule 116, “Timing and Priority”), the game checks for any of the listed conditions for
state-based actions, then performs all applicable state-based actions
simultaneously as a single event.
704.5f If a creature has toughness 0 or less, it’s put into its owner’s graveyard. Regeneration can’t replace this event.

Triggered abilities, such as that of Elvish Visionary, will still trigger. You will place the ability onto the stack as soon as you get priority, which in this case is after the creature is already dead.

Enter The Battlefield effects would still trigger, no?

@EthanTheBrave Yes, it would.


text:
Phasing vs Tribute
Does phasing allow for a Tribute to trigger twice, since the creature continues to re-enter the battle field?
For example, if I enchant my Nessian Wilds Ravager with Vanishing, does this mean that my Ravager will get to fight a second creature when he phases in (or gain an additional +6/+6)?

No, phasing won't cause Tribute or any other enters-the-battlefield abilities to trigger. A phased-out creature is treated as if it weren't on the battlefield for most effects, but phasing back in doesn't count as re-entering the battlefield.

702.25d The phasing event doesn’t actually cause a permanent to change zones or control, even though it’s treated as though it’s not on the battlefield and not under its controller’s control while it’s phased out. Zone-change triggers don’t trigger when a permanent phases in or out. Counters remain on a permanent while it’s phased out. Effects that check a phased-in permanent’s history won’t treat the phasing event as having caused the permanent to leave or enter the battlefield or its controller’s control.


text:
Is Zap A Card considered stealing if a keeper was taken from another player?
In Batman Fluxx, if Zap A Card was used to take another player's keeper, is this considered stealing a keeper?
Zap A Card is an Action card with the following text:

Choose any card in play anywhere on the table (except for the Basic Rules and any Meta Rules) and add it to your hand, unless the card you Zapped is a Creeper, in which case it goes in front of you.

To be clear, what's referring to "stealing a keeper" that needs to be tracked?

Another way of asking: in what situation in the game does it matter whether or not Zap a Card counts as "stealing a keeper"?

Do you have the wording for the card "Steal a Keeper?" I would think the ruling depends if the wording for both is the same.

Considering that "Steal a Keeper" is an Action card, and it tells you to put another player's Keeper in front of you, I'd say no. This card tells you to take any card and put it in your hand, which is also not considered in play.

But when used on "Zapped is a Creeper" it is placed in front of you. Which is the same action as "Steal a Keeper," but it is only relevant under this one set of conditions.

agreed. often times there are cards that give the same action but have different mechanisms. That seems like what's going on here. The result is the same but it's not stealing in this case unless the cards say it is stealing or unless the rules define stealing as any action that takes a card from someone else and places it in front of you.


text:
Can I use Nissa, Steward of Elements, to put out a creature with {X} in its mana cost onto the field?
I've tried to find out the answer to this online, but haven't found anything that explicitly determines it.
The exact situation is that I have a Nissa, Steward of Elements with 9 loyalty counters on it.
I want to use her +0 ability to bring in a Hungering Hydra.
What can I choose the X to be? Since she mentions "converted mana cost" can I choose X to be 8?
The closest thing I've found for a ruling is the following ruling on Flash:

If the creature has {X} in its mana cost, X is
  considered to be 0.

Does this apply to Nissa, even though she explicitly mentions converted mana costs (and Flash does not)?

No, you cannot choose a value for X. In this situation X is always considered to be 0.
Rule 107.3f says

If a card in any zone other than the stack has an {X} in its mana cost, the value of {X} is treated as 0, even if the value of X is defined somewhere within its text.

Nissa's ability checks the converted mana cost of the card, then puts it directly onto the battlefield depending on that value. When you look at that card, it is in the library, not the stack, so X is 0 and Nissa sees a value of 1 for the CMC. Then you can put it on the battlefield, and since that is also not the stack, it will enter the battlefield with 0 +1/+1 counters.
The quoted ruling for Flash has exactly the same reasoning: the card is not on the stack, so X is always 0. It has nothing to do with whether or not the card mentions "converted mana cost".


text:
How can I move the potion explosion ingredient dispenser?
When I play Potion Explosion, I want to turn the ingredient (marble) dispenser so the current player can easily see it and choose ingredients. But when I lift it, it comes apart.  I have tried gripping it from the lowest supports, but pieces still come off, marbles go everywhere, and they don't end up in the same place they were at the end of the last player's turn.
Is there a good way to pick up the dispenser and move it without it falling apart? Does glue help?  What kind of glue should be applied, and where?

Will it fit back in the box while assembled? If so, I'd use wood glue or liquid nails. Otherwise, get a small Lazy Susan :)

Yes! Gluing the joints with common Elmer's Glue makes the dispenser sturdy enough to move about when filled with marbles.

Assembled without glue, the dispenser tends to come apart:

Empty the dispenser and turn it over.

Apply glue to everywhere the supports cross each other.  I didn't put glue anywhere it would be visible from the outside:

After drying overnight, it can be filled and moved about without any trouble.  It fits into the storage box that comes with the game.

I use a lazy susan (turntable) beneath mine.


text:
Games with flipping tokens for action selection?
We are creating a game with what we think is a new action selection mechanic. The mechanic is based on poker chip like tokens that you flip to take the action the top side, then there is a different action on the bottom side. Have you encountered a similar mechanic in any other game?
Thanks in advance!

Sadly I don't think its new.
I've seen flipping discs for action selection in various games such as Mr Jack Pocket.
There are also games that when actions are taken that a token or card is flipped and another action becomes available such as Planet Defenders
Another similar to what you described is Coin Age where the options you have are literally determined by the way coins land when flipped.

Cool to know I still think the mechanic we use is slightly different and definitely pretty innovative in a euro game. So I dont worry about that. Thanks for the links!

A slightly tongue in cheek answer.
The Orchard Toys game Dinosaur Race for 3 to 6 year olds uses a similar mechanic.
In this cases the double sided tokens are of dinosaurs performing different sports. After spinning the spinner, you move the number of spaces that there are tokens showing your sport, then flip the tokens over to the reverse. The next time that sport comes up, the number will be different.
As the tokens do not all have the same sports on the reverse the number of spaces you move each time a given sport comes up can vary substantially.


text:
Acquire Movement in A Crystal Cave
Say you spend 1 boot to walk into a Crystal Cave. Then you buy a card from the Dungeon Deck that has the text at the bottom:

Acquire: 1 boot

Can you use that to leave the Crystal Cave since Acquire happens immediately?

The rules are clear.

Whenever you enter a Crystal Cave room, you become exhausted while wandering its maze-like passages and cannot use any more Boots this turn. You may still be able to move by Teleporting (described in Advanced Maneuvers), but you won’t be able to use Boots until your next turn.

(Emphasis mine)
A Crystal Cave doesn't cause you to lose unused boots; it prevents you from using any for the remainder of the turn. That means all boots on cards and Secrets played during the remainder of the turn are ignored, and so are boot gained on acquiring cards from the Dungeon Deck. You simply can't use them.


text:
Can I sacrifice a creature before the creature spell resolves?
Here is the scenario:

I cast a Goblin Piledriver.
In response, my opponent casts the Instant Murderous Cut to destroy it.
In response to that, I cast the Instant Collateral Damage intending to sacrifice the Piledriver before it can be destroyed and thus, deal damage to my opponent.

Will the sacrifice work? i.e. Can I sacrifice Goblin Piledriver out from under Murderous Cut?

You can, but not exactly in the way you think.
First, Goblin Piledriver has to resolve before it can be targeted with Murderous Cut.
Second, once the Murderous Cut is cast, it goes on the stack and hasn't resolved yet.
At that point, both players get priority, and you then could cast Collateral Damage. Now, what's important is that the sacrifice of Collateral Damage is a cost, which is paid as the spell is put on the stack. That means that your opponent can't target it with a spell (say, another Murderous Cut) before it gets sacrificed.
You both pass priority.
Collateral Damage does its, well, damage, then Murderous Cut tries to cut your goblin, but it isn't there anymore, so it fizzles.

Wow - that was fast! Thanks - here is a follow-up question. What if my opponent had played Cancel to counter the (creature) spell instead?

@JohnSatta If the creature was countered, it wouldn't be on the battlefield, so it wouldn't be able to be targeted by Murderous Cut or sacrificed to Collateral Damage

@JohnSatta You have to understand - just like instant/sorceries/etc, creature cards have to resolve before they enter the battlefield and can be targeted by things that don't specifically target spells.


text:
Order of triggered abilties
I control an Illusory Gains. My opponent casts Torch Slinger. Does my opponent get to do his kicker and damage my creature, or do I gain control of the card prior to the kicker ability and I do the kicker, or is the kicker canceled out.

What is the name of that enchantment?

Probably Illusory Gains (http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=394599)

Your opponent will get to choose the target of the damage.
Generally, players put triggered abilities on the stack in APNAP order:

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.

The "APNAP" rule means "active player, non-active player":

If multiple players would make choices and/or take actions at the same time, the active player (the player whose turn it is) makes any choices required, then the next player in turn order (usually the player seated to the active player’s left) makes any choices required, followed by the remaining nonactive players in turn order. Then the actions happen simultaneously. This rule is often referred to as the “Active Player, Nonactive Player (APNAP) order” rule.

So in your case, your opponent is the active player and casts a creature with kicker. When the creature enters the battlefield, your enchantment and the kicker ability trigger at the same time. You control the enchantment trigger and your opponent controls the kicker ability. Your opponent chooses the target for the damage and puts the ability on the stack, then you put the enchantment trigger on the stack.
The enchantment trigger resolves first and you gain control of the new creature. However, that does not change the controller of the kicker ability:

603.3a A triggered ability is controlled by the player who controlled its source at the time it triggered, unless it’s a delayed triggered ability. To determine the controller of a delayed triggered ability, see rules 603.7d–f.

So even if your opponent loses control of the creature whose ability triggered, he will still control the kicker ability on the stack.

If the creature had lifelink, who would gain the life? The new controller?  I'm guessing so since the creature is the source of the damage, even if it was being controlled by the original player.

@JonTheMon That question is answered here: http://boardgames.stackexchange.com/questions/12167/life-link-on-an-opponents-creature-by-enchantment/12168#12168

When Torch Slinger enters the battlefield, assuming it was kicked, two abilities will trigger:

An enter the battlefield trigger from Torch Slinger
An enter the battlefield trigger from Illusory Gains

The order in which they resolve does not matter. The outcome is the same either way.
Your opponent controls the first trigger. When it resolves, Torch Slinger will deal two damage to a target that your opponent chose. It does not matter who controls Torch Slinger when the trigger resolves, because the trigger exists independently.

112.7a Once activated or triggered, an ability exists on the stack independently of its source [...]

You control the second trigger. When it resolves, you will gain control of Torch Slinger.


text:
Effect of "Thran Lens" on Devotion
I want to know the effects of Thran Lens on a devotion-dependent enchantment creature, like a god or something.
I read somewhere that, when a permanent becomes colorless, the Thran Lens makes the 'cost symbols' turn into 'colorless'. With this in mind, if I have Heliod, God of the Sun on the battlefield will he ever be a creature while Thran Lens is on the battlefield?

I made some edits to your second paragraph to make the question more clear, feel free to roll it back if you don't like it.

By the way, if you write card names like [mtg:Card Name], then the system will automatically turn it into a card link. Easy, right? Someone else went ahead and did it for you this time.

Mana cost and color are two completely separate characteristics. Thran Lens only modifies the color, not the mana cost, and so Thran Lens has no effect on devotion.
Devotion

700.5. A player’s devotion to [color] is equal to the number of mana symbols of that color among the mana costs of permanents that player controls.

Mana Cost

202.1. A card’s mana cost is indicated by mana symbols near the top of the card.

Color

202.2. An object is the color or colors of the mana symbols in its mana cost, regardless of the color of its frame.

202.2f Effects may change an object’s color, give a color to a colorless object, or make a colored object become colorless

All the Thran Lens does is make permanents colorless, it doesn't change their casting costs at all. Devotion counts the number of colored mana symbols in a permanents casting cost, it doesn't care what color the permanent is.
Your Heliod will animate just fine even is everything on the battlefield is colorless assuming there are enough white mana symbols among the permanents you control.

700.5. A player’s devotion to [color] is equal to the number of mana symbols of that color among the mana costs of permanents that player controls. A player’s devotion to [color 1] and [color 2] is equal to the number of mana symbols among the mana costs of permanents that player controls that are [color 1], [color 2], or both colors.

Thran Lens or other color-changing effects have no effect on Devotion.

700.5. A player’s devotion to [color] is equal to the number of mana symbols of that color among the mana costs of permanents that player controls.

The mana symbols in a card's mana cost determine the card's color, but not the other way around.

105.3. Effects may change an object’s color or give a color to a colorless object. If an effect gives an object a new color, the new color replaces all previous colors the object had (unless the effect said the object became that color “in addition” to its other colors). Effects may also make a colored object become colorless.

The above rule covers everything about changing an object's color. Note that it does not say anything about mana symbols being changed, so nothing like that happens.


text:
Card game similar to jokers and pegs
I recently read about a popular game that, similar to Jokers and Pegs, used cards to determine play. As I recall, it required multiple decks of cards - two more decks than the number of players, but I don't think it required a board of any kind. Supposedly easy to learn, suitable for adults or children, and about equal parts chance and skill. But for the life of me, I cannot recall the name. Does this sound familiar to anyone?

Since Jokers and Pegs is a racing game, and thus requires some sort of equipment to keep track, I have no idea how you determined that the game without the equipment is "similar." What do you mean by "used cards to determine play?" This is pretty much every card game! Can you remember specifically what the winning condition or rules of play are?

Head and foot is a game that uses multiple deck and has no required accessories or board.

Why do you think this is the game in question?