text:
Can I stop a Counterspell of Goblin Grenade by sacrificing a Goblin Gardener?
I want to cast Goblin Grenade, but my opponent wants to counter it. Can I prevent them doing so like this?:

I play Goblin Grenade.
As part of the cost, I sacrifice Goblin Gardener (whose text reads: “When Goblin Gardener dies, destroy target land.”).
I use this ability to destroy one of my opponent’s 2 Islands.

Can he counter the spell, or does the destruction of the Island happen before he can play Counterspell, since it’s a direct result not of my spell itself, but of paying its cost?

You cannot prevent the Counterspell with a Goblin Gardener.
Here is what happens, step by step.

You declare you are casting Goblin Grenade and put it on the stack.
You choose the target for Goblin Grenade.
You pay the cost for Goblin Grenade. At this point, you may use any mana abilities you currently have to produce the red mana you need (or in fact, any mana at all), use any red mana you produced earlier, and you sacrifice Goblin Gardener.
Sacrificing Goblin Gardener triggers its ability, but nothing happens quite yet.
You finish casting Goblin Grenade.

Now the game checks to see if any abilities have triggered. It sees the Goblin Gardener trigger, and you put that ability onto the stack above the Goblin Grenade. You choose the target for the ability.
Now there is both a spell and an ability on the stack. Neither resolves quite yet.
Now you get priority, which means you can cast any instants or spells with flash, or activate any abilities that you want. If you do not wish to do so, you will pass priority to the your opponent, who could choose to do the same.
When your opponent gets priority, they can cast Counterspell, moving it onto the stack, choosing Goblin Grenade as the target, and tapping the targeted land to use its mana ability as part of paying the cost.
Even if they do not wish to cast Counterspell quite yet, they can also choose to activate the targeted land's mana ability, tapping it to gain the blue mana. The mana will not vanish until the phase or step ends, which will be after all spells and abilities on the stack have resolved and all players have passed priority.  If your opponent wanted to, they could tap the island, let the gardener ability resolve, and then cast Counterspell with the mana they gained. Or they could simply cast Counterspell while the Gardener ability is on the stack, and counter the Grenade before the land is destroyed.
Either way, they can easily Counterspell the grenade if they desire.

@Arthur, you are right. Fixed

A shorter version of Arcanist Lupus' answer: when you pay a cost, the specific action that is the cost happens immediately. If something has a mana cost, the mana is immediately removed from your mana pool. If sacrificing a creature is part of the cost, the creature is immediately sacrificed. The act of paying a cost doesn't use the stack, and cannot be responded to. However, anything that triggers as a result of paying the cost, rather than being the cost in and of itself, does use the stack, and can be responded to. Even though Goblin Gardener says "When Goblin Gardener dies, destroy target land", that doesn't mean that the destruction of the land occurs at the same time as the creature dying. Abilities worded "When X, Y" really mean "When X, put Y on the stack".


text:
Does my Scrabble play have to be all adjacent tiles?
Do all tiles played in one move need to be adjacent to each other? Example - there is a Y on the board, can a player place the letter E on both sides to make the word EYE ?

Related (but not duplicate) question: https://boardgames.stackexchange.com/questions/54110/was-it-ever-the-case-that-tiles-had-to-be-placed-contiguously

No, they need only be in a single line.
For example, your EYE is allowed.
The official Scrabble rules has this legitimate example for playing FARM across a previous play of HORN:

They also need to form a single word. You can't play I and O under the p and y of play in a single turn for example.

source: Stack Exchange

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text:
Can I cast Tactical Advantage multiple times on the same creature?
I'm new to Magic the Gathering. I have a question about Instants and Tactical Advantage:

Target blocking or blocked creature you control gets +2/+2 until end of turn.

Am I allowed to use 2 Tactical Advantages in a row on the same creature on the same turn, if I have enough mana? So I'd bring my creature up +4/+4.

Yes, you can cast as many spells as you want on the same creature.
The targeting requirements for Tactical Advantage are that it must be a creature you control, and it must be blocking or being blocked. Tactical Advantage changes none of these properties, so the second Tactical Advantage is just as legal to cast as the first.

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text:
Ending a two handed game
It’s my turn. It is a two handed game of Canasta.
I have three cards left in my hand. There is only one card left in the Stock pile. Can I pick up the one card and play my hand?

That's three questions.  Please ask one at a time.

While you have narrowed it down to a single question I still don't think it is clear what you are asking.

Part of the confusion may come from the fact that you are referring to the game as a "two handed game", which is not terminology I am familiar with. It generally would just be called a "two player game" rather than a "two handed game".

Yes, in two-player Canasta, when there is only 1 card remaining in the stock, you can draw that 1 card and treat that as your normal draw for the turn.
From the rules:

In two-player canasta, a situation can be reached where there is only one card remaining in the stock. In this case, the player who draws it is considered to have made a complete draw and must complete that turn as though two cards had been drawn.

Awesome!! Thank you for clarifying that for me Gendolkari

@Ka7hryn0611 You're welcome! The best way to thank someone on this site is to upvote the answer and/or accept it as correct by clicking the check mark.


text:
How many jokers can you use in a run or set in Rummikub?
Can I use two jokers in the same run or set or are you only allowed to use one joker per set or run?

You can use them all.
The only restriction on jokers in the rules is that you have to use a joker that you have replaced.


text:
Which creature deals damage with the Ninjutsu mechanic, and can I block the creature that comes in?
Ninjutsu allows you to return an unblocked creature to your hand and put a creature card from your hand into play tapped and attacking.
Does this mean if I didn't block, my opponnent could attack me again and deal damage again? Or does ninjutsu simply replace an unblocked creature, and if it was replaced the first creature doesn't do damage?
Also what happens if my opponent attacks me with a creature that can't be blocked, declare blockers step never happened so I could block the second creature that enters the battlefield tapped and attacking (the ninjustu creature)?

Only one creature deals combat damage, the unblocked creature or the Ninjutsu creature. There is no second combat phase or declare blockers step.
The complete rule for Ninjutsu is:

702.48. Ninjutsu
702.48a Ninjutsu is an activated ability that functions only while the card with ninjutsu is in a player’s hand. “Ninjutsu [cost]” means “[Cost], Reveal this card from your hand, Return an unblocked attacking creature you control to its owner’s hand: Put this card onto the battlefield from your hand tapped and attacking.”
702.48b The card with ninjutsu remains revealed from the time the ability is announced until the ability leaves the stack.
702.48c A ninjutsu ability may be activated only while a creature on the battlefield is unblocked (see rule 509.1h). The creature with ninjutsu is put onto the battlefield unblocked. It will be attacking the same player or planeswalker as the creature that was returned to its owner’s hand.

A creature can be an unblocked creature only during combat, while it's attacking, as the Ninjutsu rule and rules reminder on every Ninjutsu card says. It becomes an unblocked creature only after the declare blockers step. Once combat ends, it's no longer attacking or unblocked, so it can't be Ninjutsu'd any more.

Declare Blockers Step

509.1h An attacking creature with one or more creatures declared as blockers for it becomes a blocked creature; one with no creatures declared as blockers for it becomes an unblocked creature. This remains unchanged until the creature is removed from combat, an effect says that it becomes blocked or unblocked, or the combat phase ends, whichever comes first. A creature remains blocked even if all the creatures blocking it are removed from combat.

As for unblockable creatures: Contrary to your assumption, the declare blockers step still happens normally, you just can't assign any creature to block an unblockable creature during it. A creature becomes unblocked only after the declare blockers step, and there will not be an additional declare blockers step just because you couldn't block any creatures at that time.

it's worth noting that if the unblocked creature has first/double strike there is an opportunity to have the unblocked creature deal damage in the first strike combat step and the ninjutsu creature deal damage in the normal combat step, see the approved answer on can i activate nunjutsu between first strike and normal damage steps


text:
Can I pay to return my opponent's Shackles to their hand?
If my opponent plays Shackles enchanting one of my creatures, can I pay the {W} cost to return it to their hand?

No.
Activated abilities can normally only be activated by the controller of the permanent with the ability. When your opponent plays Shackles, even when it is attached to one of your creatures, they are still the controller of Shackles.

303.4e An Aura’s controller is separate from the enchanted object’s controller or the enchanted player; the two need not be the same. If an Aura enchants an object, changing control of the object doesn’t change control of the Aura, and vice versa. Only the Aura’s controller can activate its abilities.
110.2. A permanent’s owner is the same as the owner of the card that represents it (unless it’s a token; see rule 110.5a). A permanent’s controller is, by default, the player under whose control it entered the battlefield. Every permanent has a controller.
602.2. To activate an ability is to put it onto the stack and pay its costs, so that it will eventually resolve and have its effect. Only an object’s controller (or its owner, if it doesn’t have a controller) can activate its activated ability unless the object specifically says otherwise.

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text:
In what systems are opening 4 card majors ok?
I had several 4 card majors yesterday.  Is there a system that opens 4 card majors.  Partner says no, only in response.

There are plenty of systems that open on 4-cards, I myself play one, and that is not very uncommon here. 4-card systems are commonly used to teach Bridge. Most people prefer 5-card major though, and 4-card major feels outdated these days.
A couple of the more well-known 4-card systems are

ACOL
Standard American, originnal

"Most people" depends very much where you are, and "feels outdated" is entirely subjective; I know several people who have abandoned 5-card majors as obsolete. Good answer though.

@TimLymington I totally agree with both of observations. However, in the netherlands this is without exception the prevailing opinion, broadcast by the national Bridge Association themselves.

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text:
What's this game featuring a 15x15 peg board, and 60 pegs for the two sides?
[The game was made by my husband’s grandfather in 1974, but we don’t know the name or the rules. Each end has 60 pegs. The playing space is 15 across and 15 spaces wide. Thanks for any help you can give. We’d love to play this.]

Use of pegs instead of "stones" suggests Gramps was imitating the commercial game "Pegity", which predates Pente by a number of years.  Pegity was played on a hole grid, with pegs (all plastic when my family played it in the late 1960s and early 1970s, though apparently originally wood).
I haven't seen a set in forty years so don't recall the grid dimension.  The main play difference between Pegity and go-moku (and the later, unexpanded Pente) was four different colors of pegs, at least in the plastic version -- the game still revolved around forming a row of 5 on rows, columns, or diagonals.

looks like a slightly smaller version of Pente or go-moku, which is usually played on a 19x19 board, but can be played on 15x15


text:
Do the sides reveal their goals when the haunt begins?
On Betrayal at House on Hill, once haunt is revealed and everyone knows their parts do both sides then reveal what their ultimate goal is? Such as I , the traitor, have to release a demon and kill you all.  And do the players then say ok well we have to collect this item and do this to win?

When the haunt starts the new rules are only known by the side that they are for and not everyone.
The traitor generally leaves the room to read the rules that apply to them and it will give them some idea of what they need to do to win and what their former friends are going to do. At the same time the rest of the group will read their rules and it will give them some idea of what they need to do to win and what the traitor is doing.
The only time this changes is when a haunt lets a traitor convert other players then that player will also get to read the traitor rules and they will now know both sets of rules.

No. That's the whole point of the two different books. If both sides were getting the same set of information, you could just read one entry for both. Note that some of the information might be in both books. So if you're the traitor, then not only do you not know the players' information, you don't know if the players know some of the traitor's information. And if you're the players, not only do you not know the traitor's information, you don't know if the traitor knows some of the players' information.


text:
When do you gain life from lifelink when attacking?
When do you gain the life from lifelink when attacking?  Is it right when the attacks happen, or is it at the end of your attack phase?

You will gain the life at the same time that the damage is dealt. Lifelink simply changes what the effects of dealing are, to include gaining life.
From the basic rule book:

lifelink—If a creature with lifelink deals damage, its controller also gains that much life.

Note that some creatures, such as Horned Cheetah have a similar ability to Lifelink, but it works slightly different. As a triggered ability, Horned Cheetah's ability will go on the stack when damage is dealt, and ou will gain life after that ability resolves.
So with Lifelink... you are at 1 life, and your opponent is attacking you with 2 1/1 creatures. You can block one of them with a Vampire Nighthawk, but can’t block the other. When combat damage is dealt, you lose 1 life and gain 2 life simultaneously, so you do not lose the game.
If instead you had a Horned Cheetah to block with, then you would lose the game before you gain the life fro Horned Cheetah.

ya i meant lifelink (to much league of legends)

Ya that's how i figured it happened, thanks for the answer. :)

@cory If this answered your question (and a better answer doesn’t come along), please use the check mark to mark this as the answer

Incidentally, when Lifelink was first keyworded in Tenth Edition it was a triggered ability like Horned Cheetah has.  So they went and errataed all the old cards to have Lifelink.  Then they changed Lifelink during the M10 rules overhaul to act like it does now and de-errattaed all of the older cards that were now functionally different from lifelink... except for Loxodon Warhammer, which had been reprinted in Tenth Edition with Lifelink.

The other answer is good, I just like to reference the comprehensive rulebook. Rule 119.3 details the effects of damage being dealt. For instance, 119.3a says

Damage dealt to a player by a source without infect causes that player to lose that much life.

And 119.3f says

Damage dealt by a source with lifelink causes that source’s controller to gain that much life,
  in addition to the damage’s other results.

So a player losing life from being dealt damage, and a player gaining life from dealing lifelink-damage, are both treated equally by the rules, and happens simultaneously as an integral part of what "deal damage" means.


text:
What are the limitations on pillaging and battling a region?
How many times we can pillage or battle each region without using the Tyr's Challenge card ("As your action, you may pay 2 rage to repillage an already pillage")?
Is there a limitation?

Wow, can't believe my reading is so bad. Thanks @doppelgreener for adding the emphasis.

Possible duplicate of How often can we use Tyr's Challenge?

The rules for Blood Rage describe the phases of play, in particular with page 17:

To Pillage, choose a province that has at least one of your figures in it (or in a supporting fjord) and has not yet been successfully pillaged this phase (its Pillage token is showing the reward side up).

Ipso facto, each province may be pillaged repeatedly until a pillage is successful, and then it cannot be pillaged again.


text:
If two things say "You may pay (cost)" and I pay that cost once, do both things happen?
If I own two Flameshadow Conjurings and play a Spawn Of Thraxes, both Flameshadow Conjurings would go on the stack. Once I choose to pay 1 red mana, do I get two copies or one? Since the rules text says "if you do" it seems like both cards would see I did and I'd get two copies.

Magic abilities mean exactly what they say they do. Specifically, the two abilities on the stack do not know about one another, and they do not communicate with one another in any way. As the second ability resolves, it has no idea that the first one ever existed, or whether you chose to pay for it.

This is also a simple and clear question with a (now) good title and without many specific details, so it will make a good dupe target in the future.

If you don't pay a mana the second time you are instructed "you may pay {R}", you do not get a second token.

When the creature enters the battlefield, the abilities of both Flameshadow Conjuring trigger. You place them on the stack in the order of your choice.
Only one spell or ability resolves at a time.
First, the newest instance of Flameshadow Conjuring's ability on the stack resolves. As part of resolving, it gives you the option to pay a cost, and creates a token if you do.
Later, the other instance of Flameshadow Conjuring's ability resolves. As part of resolving, it gives you the option to pay a cost, and creates a token if you do.
Neither of these abilities care about costs payed by similar abilities in the past. They just check if you payed the cost they gave you the option of paying.


text:
Can a countered creature be regenerated?
After a creature is countered by a spell such as Counterspell can it regenerate. I was trying to counter my friend's Mortivore, but he said it could regenerate from that. So I need help trying to figure if he is lying or not.

Not sure what you are asking but if a creature is countered with a spell that has nothing to do with regeneration.

On a tangent, unless your friend is a certified judge (or something like that) then it could simply be that he is mistaken.  Being wrong doesn't make someone a liar.

No, a creature cannot use Regenerate to avoid being countered.
When your friend casts Mortivore, it goes on the Stack as a Spell.  It is not a Creature until the spell resolves and leaves the stack.
Counterspell uses the Counter keyword action, which removes a spell from the stack.  This means the spell never resolves and does not have any effect.  In the case of a creature spell, the effect is to put a creature on the battlefield; if it is countered, the creature is never created.
The abilities on a creature card (including regeneration) cannot be used until the card has finished being cast and become a creature on the battlefield*.  Therefore, Regenerate cannot be used while Mortivore is on the stack.
Since Counterspell gets rid of Mortivore while it is still on the stack, your friend cannot use Mortivore's regeneration ability to avoid your Counterspell.
Note: Even if you could use a regeneration ability from the stack, it still wouldn't apply here.  Regeneration only applies when a permanent would be Destroyed, which is different than being countered.
*Except in certain exceptional cases, none of which apply here.

Doesn't this apply to any card being countered? Until it's in play, a card only has a casting cost, color(s), and a type; the text box is n/a until it's a permanent - unless it says otherwise.

@Mazura I'm not quite sure what you mean.  Are you pointing out that this applies to enchantments, artifacts, etc. as well as creatures?  Or do you mean something else?

Counter removes a spell from the stack. This means the spell never resolves and does not have any effect. This is about how counters work, not regeneration.

Re "More broadly, it can't use any of its abilities to avoid being countered. [Except in certain situations where card text overrides the game rules.]", This line is wrong. "Can't be countered" doesn't override any game rule, yet it's an ability that can be "used" avoid it being countered. What was suppose to be the point of this line? Maybe I can help you come up with better wording.

@ikegami "Can't be countered" overrides the game rule that says that cards can be countered.  But after reading it again, I agree that my second sentence is a bit awkward.  I was trying to emphasize the difference between a creature and a creature spell w.r.t. abilities, but I think the rest of the answer covers that with more clarity.  Would it be better to just remove my second sentence altogether?

Re "Would it be better to just remove my second sentence altogether?", Yes. Spells can have abilities that can be used on the stack. Even activated ones.

There's no possible interaction between Counterspell and regeneration.
You can't use Counterspell on a creature (a creature card or token on the battlefield), only on a creature spell (a creature card or copy thereof on the stack).
Yet Mortivore's activated ability can only be activated when it's a permanent, not a spell. This is the case for most activated abilities. One can only activate an abilities of object in other zones if they are in the only zone in which it makes sense to activate the ability. (e.g. Cycling on cards such as Akroma's Blessing can only be activated from one's hand since only cards in hand can be discarded.)
In fact, regeneration can only be given to permanents (cards or tokens on the battlefield), not spells (cards or copies thereof on the stack).

109.2. If a spell or ability uses a description of an object that includes a card type or subtype, but doesn’t include the word “card,” “spell,” “source,” or “scheme,” it means a permanent of that card type or subtype on the battlefield.
110.1. A permanent is a card or token on the battlefield. [...]
112.6. Abilities of an instant or sorcery spell usually function only while that object is on the stack. Abilities of all other objects usually function only while that object is on the battlefield. The exceptions are as follows: [No exceptions apply to Mortivore's activated ability.]

You cannot regenerate a countered creature.
As a general rule, unless an ability only makes sense when applied in another zone (e.g. "return this card from graveyard to hand" clearly must work in the graveyard and "cannot be countered" must function on the stack) then that ability only applies while the card is a permanent on the battlefield.
Regenerate is one such ability. Countering a creature spell prevents it from entering the battlefield, so it never had an opportunity to be regenerated.
Furthermore, Regenerate prevents the destruction of a permanent, but countering a spell doesn't destroy it.   So even if you could use regenerate while it was on the stack the ability wouldn't do anything.

Regenerate means "The next time this creature would be destroyed this turn, instead tap it, remove all damage done to it, and if it is in combat, remove it from combat." Countering does not destroy, partially because  "destroy", like many words in magic, is a word with a very precise meaning and countering doesn't say that it destroys, and partially because a spell is not on the battlefield, and destroy is exclusively relevant to things on the battlefield. So regeneration is not applicable, the same way you can counter a creature with indestructible.


text:
Where do I get the mana from for cards that give me mana?
If I have a card like Heart Warden or Llanowar Elves that says if I tap this card, I add one green mana to your mana pool, from where I can get this card green mana?

You get the mana from the card itself, and you just remember that you have it for now.
I suspect you may be confusing lands with mana and thinking that this card gives you a forest card. They're different concepts completely. This is a common way for new players to get confused.
Mana is a currency that goes up and down during your turn. Lands, and creatures like Heart Warden, are ways to get this currency. Forests, for example, implicitly have exactly the same ability, and in fact that ability used to be written on the card:

Nowadays forests just have the symbol for green mana instead, but it means the same thing:

Forests give you green mana. Llanowar Elves will also give you green mana. To cast a spell that requires 3 mana, you can tap 2 forests and 1 Llanowar Elves to get 3 mana, then spend that 3 mana to cast the spell.
For more information on this, I suggest you read the Magic 2015 Quickstart Rules, page 4 on Lands.

There are no mana cards. There are Land cards which produce mana, and there are other types of cards, like the two you mention in your question, which also can add mana to your mana pool. Your mana pool is simply the amount of mana you have available at that moment to use. When your turn ends, it goes away.
When you tap a creature like Llanowar Elves, it adds one green mana to your mana pool just like tapping a Forest card would. You do not need an extra Forest card, nor does it imply that you add a Forest card to your available lands.


text:
What is a Conspiracy Card and how does it work?
What is a Conspiracy ability and how does this card work?: Assemble the Rank and Vile
How does Hidden Agenda work?
How do you activate Hidden Agenda?
What and Where is the Command Zone?
What do you even do with it? I cannot understand anything it is saying.

Can you clarify why you used the "mtg-commander" tag? Are you playing the Commander format, or was it just because of the words "command zone" on the Conspiracy card?

Conspiracy is a special, standalone set in MtG, currently consisting of two expansions: Conspiracy; and Conspiracy: Take the Crown.
First and foremost, I'd recommend you read these articles, which explain some of the set and its mechanics:
The Conspiracy format
The Mechanics of Conspiracy
The second article explains both what are Conspiracy cards and how Hidden Agenda works. Also, this is the official rule for Conspiracy cards:

905.4. At the start of the game, before decks are shuffled, each player may put any number of conspiracy cards from his or her sideboard into the command zone.

And here are the rules for cards with Hidden Agenda:

702.105a Hidden agenda is a static ability that functions as a conspiracy card with hidden agenda is put into the command zone. “Hidden agenda” means “As you put this conspiracy card into the command zone, turn it face down and secretly choose a card name.”
702.105b To secretly choose a card name, note that name on a piece of paper kept with the face-down conspiracy card.
702.105c Any time you have priority, you may turn a face-down conspiracy card you control in the command zone face up. This is a special action. Doing so will reveal the chosen name. See rule 115.2h.
702.105d Hidden agenda and another ability of the object with hidden agenda that refers to “the chosen name” are linked. The second ability refers only to the card name chosen as a result of that object’s hidden agenda ability. See rule 607.2d.

(Mostly) Unrelated to Conspiracy is The Commander format, from which the term Command Zone is taken. The Command Zone is a special zone in a game of Commander, where the commander (or general) of your deck begins the game.
Some Conspiracy cards reference the Command Zone, as it's a zone in the game that's reserved for objects with overarching effects on the game. See rules 408.1...

408.1. The command zone is a game area reserved for certain specialized objects that have an overarching effect on the game, yet are not permanents and cannot be destroyed.

And 408.3:

408.3. In the Planechase, Vanguard, Commander, Archenemy, and Conspiracy Draft casual variants, nontraditional Magic cards and/or specially designated cards start the game in the command zone. Each variant has its own rules regarding such cards. See section 9, “Casual Variants.”

I feel like mentioning the commander-specific rules about commander tax is unrelated to the question (emblems go in the command zone as well; but no need to mention the rules regarding emblems). It adds some clutter to an already long/detailed answer.

I debated whether I should say something about it or not. I decided to post it like this because the question, although talking about Conspiracy, is tagged with [tag:mtg-commander]. I can edit it out if you feel it's not related to the question, though.

I didn't notice the tag. Possible that the asker used the tag because of the word "command" in the conspiracy card text; not realizing that "commander" is a different format. Hopefully the user can clarify.

I do think beginning to explain how the commander mechanics work is unnecessary; the question's just about conspiracy and the command zone and a separate variant's mechanics have nothing to do with it. At worst it might wind up confusing a reader into thinking you have to pay {2} to use a conspiracy somehow.

I've removed the bits that were specific to a game of Commander, then. I believe the answer is now more fitting to the question.

The Command Zone is one of the zones in Magic, just like the battlefield, deck, hand, graveyard, stack, and exile.

Command

408.1. The command zone is a game area reserved for certain specialized objects that have an overarching effect on the game, yet are not permanents and cannot be destroyed.
408.2. Emblems may be created in the command zone. See rule 113, “Emblems.”
408.3. In the Planechase, Vanguard, Commander, Archenemy, and Conspiracy Draft casual variants, nontraditional Magic cards and/or specially designated cards start the game in the command zone. Each variant has its own rules regarding such cards. See section 9, “Casual Variants.”

The rules for conspiracy cards are mostly given in the reminder text. It simply means that the card starts in your command zone. Also, conspiracy cards are not part of your deck (they come directly from your sideboard).

905.4. At the start of the game, before decks are shuffled, each player may put any number of conspiracy cards from his or her sideboard into the command zone.

So any conspiracy cards that you draft can by placed in your command zone. These cards will help you in various ways, while not actually being in your deck.
A conspiracy with hidden agenda just means that the conspiracy card starts face down, and is known only to you. They all involve you secretly choosing a card name, and then having an effect on cards with that name.

905.4a Conspiracy cards with hidden agenda are put into the command zone face down. Any time a player has priority, he or she may turn a face-down conspiracy card he or she controls face up. See rule 702.105, “Hidden Agenda.”
702.105a Hidden agenda is a static ability that functions as a conspiracy card with hidden agenda is put into the command zone. “Hidden agenda” means “As you put this conspiracy card into the command zone, turn it face down and secretly choose a card name.”
702.105b To secretly choose a card name, note that name on a piece of paper kept with the face-down conspiracy card.
702.105c Any time you have priority, you may turn a face-down conspiracy card you control in the command zone face up. This is a special action. Doing so will reveal the chosen name. See rule 115.2h.
702.105d Hidden agenda and another ability of the object with hidden agenda that refers to “the chosen name” are linked. The second ability refers only to the card name chosen as a result of that object’s hidden agenda ability. See rule 607.2d.


text:
How to deal with Legendary tokens?
Can you have more than one "Legendary Token"? I don't think so, but I have a creature named Tolsimir Wolfblood that allow me to tap it to create a 2/2 Legendary Wolf token named Voja.
If you can't have more than one legendary creature on the field, would you have to sacrifice the wolf token or Tolsimir Wolfblood? How does that work?
Are legendary tokens and legendary creatures different from each other? Or is it that legendary creatures can't have the same name as the other?

Flavorwise, Tolsimir has a wolf companion, and if that wolf dies, Tolsimir can tap to resurrect it. But if the wolf is already on the battlefield, Tolsimir can't create a second one.

I believe you've misinterpreted the "Legend Rule", which is CR 704.5j (emphasis mine):

704.5j If a player controls two or more legendary permanents with the same name, that player chooses one of them, and the rest are put into their owners’ graveyards. This is called the “legend rule.”

You can have as many legendary permanents as you want, as long as they have different names. Some cards, like Brothers Yamazaki and Mirror Gallery can ignore that rule.
Also, you can read Tolsimir Wolfblood's rulings in its gatherer page:

7/1/2013: The “legend rule” means that creating a second Voja while one is already under your control will result in one of them being put into its owner’s graveyard (where it promptly ceases to exist). You choose which of the two remains on the battlefield and which is put into the graveyard.

In your specific case, you can only have one Voja token, and only one Tolsimir Wolfblood, but both permanents can coexist on the battlefield.

Tolsimir Wolfblood's ability reads:

: Create a legendary 2/2 green and white Wolf creature token named Voja.

The rule for the legendary supertype reads:

704.5j If a player controls two or more legendary permanents with the same name, that player chooses one of them, and the rest are put into their owners’ graveyards. This is called the “legend rule.”

Note that the rule specifies they have to have the same name. If you use Tolsimir's ability, you will have two legendary creatures, one named Tolsmir Wolfblood and one named Voja. Since they have different names, they both stay on the battlefield. If you use Tolsimir's ability again to create a second Voja token, you have to destroy either the new token or the old one, since you will have two Voja on the battlefield at the same time.
Three magic cards have modified this rule:

Brothers Yamazaki do so because they are identical twin brothers, so you can have one, or both of the brothers out at the same time. They specifically ignore this rule when there are two of them exactly in play. This was not changed when the legend rule was adjusted to allow one copy per player, so if two players each have one out and one of those players plays a second one (third total) that player will have to sacrifice one until they are following the current legend rule.
Mirror Gallery simply removes the legend rule from the game while it's in play, allowing unlimited copies of legendary permanents in play. If Mirror Gallery leaves play it immediately applies again and any duplicate legendaries need to be sent to the graveyard.
Sakashima of a Thousand Faces works exactly like Mirror Gallery does, except it only applies to you, not to the entire game. Just like Mirror Gallery you can have as many copies of the same legendary permanents in play as long as Sakashima is in play, but the rule applies as soon as Sakashima leaves the battlefield.

I have four of the Tolsimir Wolfblood's They are awesome creatures if you can get them out lol.  My friends when we play always target me so i never get a chance to play them so I get very sad very very sad.

@DylanParris take a look at Wren's Run Packmaster I like this one for making powerful wolves


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What happens to Poison Counters after the Player that gave them leaves the game?
If a player playing with infect loses the game are the poison counters they have dealt out removed, similar to how curse enchantments they own would leave the game. Or do they remain, similar to how a -1/-1 counter on a creature would stay?

They remain on the player who has them. Counters are not owned by the player that created them, they just are there once created and are not removed unless an effect specifically says to remove them. That means that even if only one player is using infect and is removed from the game proliferate can still cause another player to lose due to poison.
There is only one thing in magic that actually removes poison, the card Leeches.
A new game started with Karn Liberated will not keep the counters a player had when the new game begins. These counters, like everything else in the original game cease to exist.

legend. Explains it perfectly.

There is actually one other thing / card in the game that removes poison counters... Karn Liberated and restarting the game.

@GendoIkari Technically it does not remove the counters, they cease to exist along with the rest of the original game. I'll update my answer to mention it though.


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How do emblems work?
Jace, Unraveler of Secrets allows you to create an emblem that will cause the first spell to be countered every turn for your opponents.  Does this continue even if he is destroyed? Is there a way to counter or remove its effect?

The Emblem will stay forever, even if Jace is destroyed.

Emblems

113.1. Some effects put emblems into the command zone. An emblem is a marker used to represent an object that has one or more abilities, but no other characteristics.
113.2. An effect that creates an emblem is written “[Player] gets an emblem with [ability].” This means that [player] puts an emblem with [ability] into the command zone. The emblem is both owned and controlled by that player.
113.3. An emblem has no characteristics other than the abilities defined by the effect that created it. In particular, an emblem has no name, no types, no mana cost, and no color.
    113.4. Abilities of emblems function in the command zone.
113.5. An emblem is neither a card nor a permanent. Emblem isn’t a card type.

There is nothing in the game currently that can remove an emblem. (Other than restarting the game with Karn Liberated). There shouldn't be any rule preventing the existence of a card that said something like "Exile target Emblem", but no such thing exists.

Restarting the game (i.e. with Karn Liberated) will, depending on your definition, get rid of the emblem.

@TheThirdMan Karn seems to just ruin every statement that starts with "there's no way to..."


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What is a land creature?
Halimar Tidecaller in card text it says Land creatures you control have flying.  Does this mean any creature without flying or does it mean a land which is also a creature

A permanent which is both a land and a creature.
Let's together find out what they exactly mean with 'land creatures'.
In the Comprehensive Rules we find the following regarding multiple card type:

205.2b Some objects have more than one card type (for example, an artifact creature). Such objects satisfy the criteria for any effect
  that applies to any of their card types.

Meaning that in this example the object benefit from being an artifact as well as a creature. But on the flip side..

300.2. Some objects have more than one card type (for example, an artifact creature). Such objects combine the aspects of each of those
  card types, and are subject to spells and abilities that affect either
  or all of those card types

So they are also approachable by all the types the card currently has.
But we want to know what cards are being affected by Halimar Tidecaller static ability ("Land creatures you control have flying."). Does that mean all lands or all creatures or all lands that are also creatures?
It says on the card 'Land creatures you control' which indicate that any object that satisfy that criteria is affected. So not just lands or not just creatures, but only 'land creatures'.

Although neither previous answer is wrong, I feel that the first sentence in both is a little misleading. My version:
It is a permanent which is both a land and a creature.
The distinction is that it's not more true to say "it is a land which is also a creature" than it is to say "it is a creature which is also a land".
The simplest example is the card Dryad Arbor. This is a card that has both the type "land" and the type "creature", which means that it has all the properties of both.
As others have pointed out, other common ways to have an object be both a land and a creature is the Awaken mechanic and "man lands" that can become creatures.
A regular creature can also become a land creature, through things such as Life and Limb.

It means lands which are also creatures.
Halimar Tidecaller is from the Battle for Zendikar block. Both the original Zendikar block, and the newer Battle for Zendikar block, have a sort of low-scale theme for land creatures, having many spells and effects which turn lands into land creatures. Pointed examples include the "manlands" and the Awaken mechanic.
Halimar Tidecaller is describing permanents you control with the "land" and "creature" qualities, just like Paragon of Gathering Mists is describing permanents you control with the "blue" and "creature" qualities. If they meant creatures without flying they would have used the "creatures without flying" phrase.
You might notice Halimar Tidecaller also gives you back a "card with awaken". That's referencing the Awaken mechanic. Halimar Tidecaller is made mainly for decks that care about using that mechanic, and want to re-use spells that have it.

The short answer is it is an object on the battlefield that is both a land and a creature at the same time.
Halimar Tidecaller was printed in the same set as cards with the ability awaken, for example Ruinous Path. These cards had an alternate cost that would do the main effect and also awaken one of your lands as a creature, that land would still be a land, making it into a land creature.
This is not the first time there have been cards that were both land and creature, Dryad Arbor is probably the most notable example, being the only card that was printed as both, but many cards like Mutavault are lands which have an ability to temporarily turn them into creatures. There are also some enchantments that do this, such as the 6 Genju cards of Kamigawa Genju of the Realm and the 5 Zendikon of Zendikar Wind Zendikon. Life and Limb combines saprolings and forests, making them all land creatures. Finally there are planeswalkers that make lands into creatures like Koth of the Hammer.


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Who chooses the targets for Captain's Maneuver?
Our discussion was two fold.  Who gets to direct the damage (pick a new target) and let's say it was cast before combat damage was assigned.  Who determines which damage gets redirected.  The active player or the owner of the spell.  My assumption is the person who cast the spell determines which damage and where to redirect it.
Captain's Maneuver: The next X damage that would be dealt to target creature or player this turn is dealt to another target creature or player instead.

Curious about why there was confusion... why do you think the active player would have a choice here? If someone casts Lightning Bolt, is there uncertainty as to if the active player gets to direct the damage?

The controller of the spell (who is the person that cast it) gets to decide which creature's damage is replaced, and where that damage goes.
When you cast a spell, you choose the targets for that spell. In the case of Captain's Maneuver, there are 2 targets that you choose. One is the creature that would receive damage, and the other is the creature that receives the damage instead. This works the same with Captain's Maneuver as it would with any other targeted spell such as Lightning Bolt.

Casting Spells

601.2. To cast a spell is to take it from where it is (usually the hand), put it on the stack, and pay its costs, so that it will eventually resolve and have its effect.

601.2c The player announces his or her choice of an appropriate player, object, or zone for each target the spell requires.

I don't know if the OP meant to ask about this (the question isn't specific) but beyond just picking the targets, there's also the question of how to decide which damage is redirected if more than X is dealt simultaneously. That could matter if there are abilities like deathtouch involved.


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Can Bruna, Light of Alabaster take my opponent's auras?
Bruna, Light of Alabaster says:

Whenever Bruna, Light of Alabaster attacks or blocks, you may attach to it any number of Auras on the battlefield and you may put onto the battlefield attached to it any number of Aura cards that could enchant it from your graveyard and/or hand

It appears that you could attach enchantments you do not control taking them from other creatures you do not control. Is this correct?

Yes, this is true for all auras on the battlefield, regardless of their controller. There's no general rule that Auras can only be attached to their controller's own permanents, so Bruna can 'steal' other player's auras.
(They'd still control them, which is relevant e.g. for Curious Obsession. This gives an ability to the enchanted creature, so you would get to draw a card if you 'steal' your opponents Curious Obsession with Bruna and deal combat damage to a player. But, as @Arthur notes in the comment, your opponent might not attack the next turn, which causes him/her to sacrifice the aura because he/she still controls it.)
You might think this is too powerful, but it really isn't; auras generally see little competitive play because they tend to lead to card disadvantage (if the enchanted creature dies, you'll lose two cards at once). And a multicolored six mana card should better win the game for you; it's supposed to be your 'finisher'. Commander is more about fun and long multiplayer games, so there this card certainly has more potential.

Note that if I attack with Bruna, and take an opponent's Curious Obsession, then I draw cards when Bruna deals combat damage to my opponent (because I control Bruna, and it is Bruna who gets the ability, meaning "you" refers to me), but my opponent may withold from attacking for a turn and the Obsession will be sacrificed (because my opponent still controls the Obsession, so that "you" refers to him / her).

Good point, thanks. So this single card suffices to show some of the shenanigans about controlling auras :)

"auras generally see little competitive play because they tend to lead to card disadvantage." If the "card disadvantage" is the aura card, then this is just saying that auras aren't as good as other cards, making your statement "auras generally see little competitive play because they aren't as good as other cards". And since  Bruna takes cards from your graveyard, you don't have to draw the auras, you just have to get them into your graveyard.

Oh, if you play Bruna, you should definitely play a lot of auras in your deck. I'm just talking about the general picture; your opponent isn't likely to play many of them.

@Acccumulation generally when people are talking about card disadvantage from auras they are thinking of how you set yourself up for 2-for-1's. If an opponent removes your enchanted creature, they spent 1 card to remove two of your cards, that sort of thing. That isn't to say there aren't ways that aura's are designed to mitigate this (giving a powerful/card-advantage/protection effect etc.)


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Activated ability of Golden Guardian
Can the ability of Golden Guardian be activated at any time? Say, during another player's turn or during an attacker's or blockers fast effects phase?

Yes. (116.1b).  Can you describe why you think you wouldn't be able to activate this ability at those times?

What is an "attacker's or blocker's fast effects phase"? Do you mean the point after attackers or blockers are declared where their abilities go on the stack and players can cast spells? (That is not a phase, and it is not called a fast effects phase.)

"fast effects" apparently is something from Yu-Gi-Oh. I guess they mean after declaring attackers and/or blockers

"Fast effects" is an obsolete Magic: the Gathering term, and I can see why it would be confusing for someone who played in that era.

Yes, activated abilities can by activated at any time you have priority, unless the ability states otherwise, which is not the case with Golden Guardian. This is per Comprehensive Rules:

112.3b Activated abilities have a cost and an effect. They are written as “[Cost]: [Effect.] [Activation instructions (if any).]” A player may activate such an ability whenever they have priority. (...)


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How do indestructible creatures actually work?
If a First Striker does lethal damage to an indestructible creature, does this remove the creature from combat so it can not deal any damage?
Another scenario: An indestructible creature is dealt lethal damage, has destroy cast on it, or is hit during combat by a creature with deathtouch. Would casting Lava Coil in the second main phase cause it to be exiled?

No, indestructible is different from regeneration. An indestructible permanent simply ignores lethal damage and destruction effects and stays in combat.

702.12b A permanent with indestructible can’t be destroyed. Such permanents aren’t destroyed by lethal damage, and they ignore the state-based action that checks for lethal damage (see rule 704.5g).

A creature is removed from combat when it is regenerated, among others. Regeneration is superficially similar to indestructible, but still different. For example, regeneration removes all damage marked on a regenerated creature, while an indestructible creature retains all damage marked on it until it gets removed during the next cleanup step.
Note that an indestructible creature still dies when its toughness goes to zero (such as through -X/-X effects like Grasp of Darkness), or when it is sacrificed. If someone cast Lava Coil on an indestructible creature and it would die later that turn, it would indeed be exiled, even if Lava Coil itself couldn't kill that creature.


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What's the timing on Warrior en-Kor's damage redirection?
Say I have Warrior en-Kor out and use its ability to redirect the next 5 damage it would get. I leave it as-is, and then in combat resolution a creature would deal 6 damage to it, leaving all but 1 damage redirected. Would I be assuming correctly that I cannot redirect that 1 damage later?

It doesn't transfer damage that's anyway been dealt; it changes what will receive damage

By "later", do you mean "after I have already used the ability to redirect the other damage" or "after the damage has already resolved"?

You cannot redirect damage after it has been dealt. The only card that ever did this was Simulacrum which now lets you gain the life lost from damage dealt to you back and then simulacrum deals damage to a target instead.
Redirection creates a replacement effect, all of the en-Kor creatures had this effect. It's been reworded to no longer talk about redirection, which is considered obsolete, the new en-Kor ability is written this way:

The next 1 damage that would be dealt to ~ this turn is dealt to target creature you control instead.

The new wording makes it much more clear that you have to activate the ability before the damage is dealt, since it refers to the "next" damage. So timing is the last time you have priority when the spell that would do the damage is on the top of the stack (other than Sudden Shock and Molten Disaster, which you would need the redirection active before it is cast due to split second) or when you have priority after blockers are declared but before damage is assigned (no priority to activate between assigning and dealing damage).

Yes, to redirect damage with Warrior en-Kor, you have to ativate its ability before damage happens.
That's because damage redirection is a kind of replacement effect, and replacement effects have to be active before the event they replace happen.


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What happens if a creature that would fight isn't on the battlefield anymore?
Ulvenwald Tracker is a specific example of a creature with an activated ability for the fight mechanic. If this ability is activated and put on the stack, but then Ulvenwald Tracker is destroyed somehow, does the fight ability still resolve given he no longer exists?

It depends what the targets are.  The ability will resolve, but it may not do anything.
Scenario 1:

You activate Ulvenwald Tracker targeting your Grizzly Bears and your opponent's Runeclaw Bear
Your opponent responds with Lightning Bolt targeting your Tracker

In this case, the Tracker dies, but that doesn't affect anything.  The Tracker's ability resolves and the two Bears fight each other and both die.
Scenario 2:

You activate Ulvenwald Tracker targeting itself and your opponent's Suntail Hawk
Your opponent responds with Lightning Bolt targeting your Tracker

In this case, the Tracker's ability still resolves, but it doesn't do anything.  Spells and abilities don't track targets when they change zones.  That means that when the Tracker's ability resolves, the Tracker is no longer a legal target.  The ability still has at least one legal target (the Suntail Hawk), so it resolves.  It attempts to do as much as it can with the remaining targets, but the Hawk doesn't have anything to fight, so nothing happens.

This answer only addresses how abilities resolve with targets, and not how fight abilities work if one of the creatures leaves the battlefield.

The ability resolves normally if the target still exists.

112.7a Once activated or triggered, an ability exists on the stack independently of its source. Destruction or removal of the source after that time won’t affect the ability. Note that some abilities cause a source to do something (for example, “Prodigal Pyromancer deals 1 damage to target creature or player”) rather than the ability doing anything directly. In these cases, any activated or triggered ability that references information about the source because the effect needs to be divided checks that information when the ability is put onto the stack. Otherwise, it will check that information when it resolves. In both instances, if the source is no longer in the zone it’s expected to be in at that time, its last known information is used. The source can still perform the action even though it no longer exists.

(Emphasis mine.)
This means the the two creatures fight. But the fight has no effect.

701.12. Fight

701.12a A spell or ability may instruct a creature to fight another creature or it may instruct two creatures to fight each other. Each of those creatures deals damage equal to its power to the other creature.

701.12b If a creature instructed to fight is no longer on the battlefield or is no longer a creature, no damage is dealt. If a creature is an illegal target for a resolving spell or ability that instructs it to fight, no damage is dealt.

701.12c If a creature fights itself, it deals damage to itself equal to twice its power.

701.12d The damage dealt when a creature fights isn’t combat damage.

(Emphasis mine.)

If neither of the targeted creatures exist as the ability would resolve, it will be removed from the stack instead of resolving.

608.2b If the spell or ability specifies targets, it checks whether the targets are still legal. A target that’s no longer in the zone it was in when it was targeted is illegal. Other changes to the game state may cause a target to no longer be legal; for example, its characteristics may have changed or an effect may have changed the text of the spell. If the source of an ability has left the zone it was in, its last known information is used during this process. If all its targets, for every instance of the word “target,” are now illegal, the spell or ability doesn’t resolve. It’s removed from the stack and, if it’s a spell, put into its owner’s graveyard. Otherwise, the spell or ability will resolve normally. Illegal targets, if any, won’t be affected by parts of a resolving spell’s effect for which they’re illegal. Other parts of the effect for which those targets are not illegal may still affect them. If the spell or ability creates any continuous effects that affect game rules (see rule 613.10), those effects don’t apply to illegal targets. If part of the effect requires information about an illegal target, it fails to determine any such information. Any part of the effect that requires that information won’t happen.
Example: Sorin’s Thirst is a black instant that reads, “Sorin’s Thirst deals 2 damage to target creature and you gain 2 life.” If the creature isn’t a legal target during the resolution of Sorin’s Thirst (say, if the creature has gained protection from black or left the battlefield), then Sorin’s Thirst doesn’t resolve. Its controller doesn’t gain any life.

Example: Plague Spores reads, “Destroy target nonblack creature and target land. They can’t be regenerated.” Suppose the same creature land is chosen both as the nonblack creature and as the land, and the color of the creature land is changed to black before Plague Spores resolves. Plague Spores still resolves because the black creature land is still a legal target for the “target land” part of the spell. The “destroy target nonblack creature” part of the spell won’t affect that permanent, but the “destroy target land” part of the spell will still destroy it. It can’t be regenerated.

(Emphasis mine.)


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Can we add to the stack after resolving part of it?
Been playing Arena in MTG and it seems to allow casting of spells after resolution on the stack.  This does not seem to follow the rules as written.  Which is right.
For example three spells are on the stack and both people pass.  the first one resolves and you are allowed to continue casting and add to the stack even though you had already begun resolving.

Could you [edit] your question to include more details? After a spell or ability resolves, a player may of course cast another spell.

Allowing casting after resolution is according to rules as written. The relevant rules are 117.1a for when a player can cast a spell, and 117.3b which states that the active player get priority after spell resolution.

117.1a A player may cast an instant spell any time they have priority. A player may cast a noninstant spell during their main phase any time they have priority and the stack is empty.
117.3b The active player receives priority after a spell or ability (other than a mana ability) resolves.

So all players can cast add instants to the stack after the resolution of any spell or ability, although no non-instant can be cast until the stack is empty.

Yes, you can always cast spells after something on the stack resolves.
It seems as though your interpretation is that players add to the stack until they're done, and then the entire stack resolves from top to bottom until it's empty in one uninterruptible procedure. But that's not how it goes; there is no unstoppable stack-resolves-until-it's-empty mode we enter.
Instead, we just opt to let the top spell or ability on the stack resolve (via each player passing in succession). When it does resolve, the active player gets priority again, and can either add a new spell or ability to the stack, or can pass it to let others add something new to the stack.
This is actually integral to some abilities functioning properly: if you put two Shocks on the stack targeting my Snapping Sailback, requiring the stack to resolve as a whole would see my Snapping Sailback killed (it dies for having 4 toughness and 4 damage marked on it). But instead it works out like this:

We let the top thing on the stack resolve, which is one of the Shocks. 2 damage is dealt to the Snapping Sailback. (The stack is now just one remaining Shock.)
Someone gets priority. As part of that, we check triggered abilities, and Snapping Sailback's triggered ability goes on the top of the stack. (The stack is now Shock, SS's ability.)
We let the top thing on the stack resolve again: Snapping Sailback's triggered ability resolves, giving it a +1/+1 counter. It's now a 5/5. (The stack is now just one Shock again.)
We let the last thing on the stack resolve: the Shock deals 2 damage to Snapping Sailback. It survives. (The stack is now empty.)
Its ability triggers again and is put on the stack, then we let it resolve, making Snapping Sailback a 6/6.


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Can I use the red 5 to move someone out of their safety zone?
I'm playing Sorry! The Disney Edition. If I am the red player, and I get a red 5 card (lets people move opponents backwards 5). Can I move someone out of their safety?

The rules for this game are terrible.  If I were to play this game with one of my groups we would allow this action because they need to follow the rules to the letter.  The other group I play with, would honour the spirit of the "Safey" zone to mean that it was "safe from effects".  Either way is perfectly fine as long as you are all following the same rules.

Yes. According to the fifth page in the official rules for Sorry! The Disney Edition, you can move out of the Safety Zone with a backwards move card. The rules also state that you can use backward move cards on other players when the card says you can. Therefore, it is heavily implied, if not explicitly said, that a backwards move card can be used to move a player's piece from their Safety Zone back onto the board.
According to the fifth page of the rules:

"Safety Zone: Only you may enter your SAFETY ZONE. You cannot enter the SAFETY ZONE by a backward move; however, you may move backward out of the SAFETY ZONE and, on later turns, move back in as cards allow."

A piece may not move out of its Home position for any reason, also according to the fifth page in the rules.

The exact quote if you wish to incorperate it into your answer: "Safety Zone:
Only you may enter your SAFETY ZONE. You cannot enter the SAFETY ZONE by a backward move; however, you may move backward out of the SAFETY ZONE and, on later turns, move back in as cards allow."

Np, I have a handy little screenshot tool that converts pictures of text into copy/pasteable text, very convenient I find.


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If a spell tells me to draw then discard a card, can I cast it before discarding it?
Suppose I have only Force Away in hand, then cast it. It says "you may draw a card then discard a card". Am I able to cast the drawn card which leaves me with no cards in hand to discard, or am I not allowed to cast it? What happens?

Perhaps wait a bit before selecting an answer. Discourages other answers...

I also found Can I cast a spell while another spell or ability is resolving? which is probably a better dupe target.

@Eric People can still change accepted answers, so I think rather instead it's better to see it as a challenge to provide a better answer.

@Doppelgreener. Agreed, but for a new user, less likely. Just a thought. I was on the old Draw3Cards for years and we often promoted the idea of holding off a bit. Point taken, though.

No, you can't cast a spell in the middle of that draw-then-discard instruction.
Whilst a spell or ability is resolving, players can't do anything that the spell or ability doesn't tell them to do. This means you draw, then discard, then afterwards you'll get a chance to cast spells. If Force Away was the last card you had, you're back down to a hand size of 0 with no cards to cast.
Magic's system for casting and resolving spells involves some concepts of the stack and priority, which you can read about here. Understanding that system is pivotal to understanding when you can/can't cast spells, and the post I'm linking to there is what had me understand it when I started out playing.
This type of ability is colloquially called "looting" — it's not meant to give you more cards than you had before, it just gives you a chance to swap out a card that isn't useful right now for one that is. It also adds cards to your graveyard which can be helpful. As you might know, Force Away came from Khans of Tarkir which also featured the Delve mechanic — one extra card in your graveyard is one extra card to delve with later.
There's an exception: cards with Madness allow you to cast them for their Madness cost as a result of discarding them. So if you happened to draw then discard Distemper of the Blood, that's an opportunity to cast it, meaning you did wind up with one extra spell to cast.

The way you describe madness might be misleading. Madness has two parts: a replacement effect that has you discard the card into exile, and a triggered ability that allows you to cast the spell. So you're not really casting it while discarding it.

@murgatroid99 Oh, right!! They changed it; it was different before SOI. I'll update.

They did change Madness in SOI, but not significantly. The only difference is that you can no longer choose whether to discard to exile. It was always a replacement effect and a triggered ability.

@murgatroid99 Oh, huh. The old reminder text makes it look like it used to be just one triggered ability (optionally replace hand->graveyard with hand->cast->stack)

@doppelgreener Nope, before it was may replace hand->grave with hand->exile and must cast if you do now it is must replace hand->exile then may cast else exile->grave


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2 players. Can I play the draw 2 after a draw 4 if it was the last card to the previous player?

If the first player has their last card as a draw 4 wild card and says uno out,can the next player ask for a color to possibly counter with a draw 2 of the corresponding color said by the first player?

Can you be more specific,I don't understand your answer.

The game is over as soon as a player plays their last card so nothing can be done in response.


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How can I resolve my Dragon Shield sleeves being curved?
I've always used Dragon Shield for sleeving my decks and recently I've noticed the sleeves come slightly curved in the box. This means when I sleeve my decks they sometimes slide and fall on the floor. I've tried stacking books on them to make them stay flat but it doesn't help much as they never stay. I was just wondering whether anyone else had this problem and what they did about it, I noticed that putting them in a particularly tight box can help, but it also sometimes bends the cards which I don't want.

Are you double sleeving?

This answer comes from personal experiences I've had with using Dragon Shield sleeves, so it shouldn't be taken as fact, since the sleeves from different batches can vary.
First things first, I'd recommend always using Matte sleeves, for several reasons:

I find them much easier to shuffle;
They don't get as grimy as smooth sleeves;
They don't tear as easily as smooth sleeves;
They don't get as curved as smooth sleeves.

For the specific problem of curved sleeves, I've tried many solutions over the years, and some seemed to work better than others.
One thing that worked best for me for straightening both sleeves and cards was to weight them down with a couple heavy books over a warm surface. I usually use a hair drier to warm up a metal surface, and then keeping it warm while the cards and/or sleeves are being weighted down. This works great for a couple cards/sleeves, but it's a lot of work for a whole deck.
Also, sleeving the cards with a "perfect size/fit" (the inner sleeves that go inside the outer sleeves) makes them slightly less bendy, which could help in straightening out your outer sleeves.
As you said, storing the whole (preferably double-)sleeved deck in a tight fitting deckbox also helps with straightening out both sleeves and cards.

P.S.: To whomever it may concern, I am thinking of opening this answer as a community wiki, so everyone can chip in with their own experiences on the subject. What do you guys think?


text:
Do you have to sacrifice a transformed creature put into play via Through the Breach?
If I put Thing in the Ice into play via Through the Breach, and it transforms during my turn, do I have to sacrifice Awoken Horror at the beginning of the next end step?

Yes.
From the Comprehensive Rules:

711.12. When a double-faced permanent transforms, it doesn’t become a new object. Any effects that applied to that permanent will continue
  to apply to it after it transforms. Example: An effect gives Village
  Ironsmith (the front face of a double-faced card) +2/+2 until end of
  turn and then Village Ironsmith transforms into Ironfang. Ironfang
  will continue to get +2/+2 until end of turn.

Yes.
A transformed creature is the same creature it was before. Auras don't fall off and temporary effects don't go away.
Now, "exile and return transformed" cards leave play, so they will enter as new objects.


text:
If a creature enters as a copy, does it have summoning sickness?
If I play the Phantasmal Image as a copy of any other creature (that has no summoning sickness), will it have the summoning sickness or not?
Phantasmal Image

You may have Phantasmal Image enter the battlefield as a copy of any creature on the battlefield, except it's an Illusion in addition to its other types and it gains "When this creature becomes the target of a spell or ability, sacrifice it."

I know that copies does not copy the "summoning sickness" status, but what if it enters the battlefield and is not being copies inside it?

Summoning sickness is not a copiable value. In fact it's not even a value at all, it's just an informal way to refer to the following rule:

302.6. A creature’s activated ability with the tap symbol or the untap symbol in its activation cost can’t be activated unless the creature has been under its controller’s control continuously since his or her most recent turn began. A creature can’t attack unless it has been under its controller’s control continuously since his or her most recent turn began.  This rule is informally called the “summoning sickness” rule.

So, “summoning sickness” is a game rule process. (We informally say summoning sickness is something a creature has, but that's informal.)
When any new non-Hasty creature enters the battlefield during your turn, since you haven't controlled it since the beginning of your turn, you can't attack with it or tap it for {T} costs. This applies for any creatures, including those that happen to be copying another.


text:
Why is my Deck not legal for Frontier?
I'm using www.deckstats.net to play around with my cards and making different decks. I'm very new to MTG and deck building.
Here is my deck so far:
//Lands
4 Dragonskull Summit
10 Mountain
11 Swamp

//Spells
1 Chandra, Pyromaster
1 Cobbled Wings
1 Firecannon Blast
1 Flame Lash
1 Hungry Flames
1 Raise Dead
1 Shadowed Caravel
1 Skulduggery
1 Spreading Rot
1 Thaumatic Compass
2 Untamed Hunger
1 Vanquish the Weak
1 Wrangle

//Creatures
2 Alley Strangler
1 Battle Squadron
1 Bishop of the Bloodstained
1 Blight Keeper
2 Bloodhunter Bat
1 Boggart Brute
1 Dune Beetle
1 Falkenrath Reaver
1 Foundry Street Denizen
1 Goblin Ringleader
2 Gravedigger
1 Nightmare
3 Ruin Rat
1 Rummaging Goblin
1 Sengir Vampire
1 Shivan Dragon
1 Skittering Heartstopper
1 Skymarch Bloodletter

Deckstats says this is not a valid Frontier deck...why is this? What cards are illegal?

The deckstats link was more helpful than the inline list (though I understand the change) deckstats showed the set symbols which told me immediately what cards were illegal.

@Andrew Link is still in there just moved it down to the last paragraph

@Malco Ahh missed that

@Sam, as an observation beyond the legalities, I think you're a little land heavy. 23 lands should work for this deck, and it would bring you to the 60 card minimum, though you still have to remove or replace the two in my answer for format restrictions.

alright thanks. i'm still in the middle of getting new cards, replacing cards i don't like, and balancing. so it's a little unbalanced and random right now.

@sam No problem. Deckstats is a good tool, it shows the set symbols by default for the most recent printing of the card, in this case the set symbols for your two illegal cards were the Goblins vs Merfolk dual deck. if it says it's illegal, look at the ones with weird set symbols and check them out.

@Sam and remember tomorrow is Rivals of Ixalan prerelease. You'll have a few new options soon.

Goblin Ringleader and Battle Squadron were not printed in anything that's legal in Frontier. Though they do have a recent printing, it's in a dual deck, which does not make it Frontier legal. The only cards that are not in sets since M15 which are Frontier legal are cards in Welcome decks or Planeswalker decks.

Technically the Planeswalker decks are considered in the set, though their exclusive cards are numbered above the top of the set.


text:
Tidal Warrior and Islandwalk
Tidal Warrior has an ability which says:

{T}: Target land becomes an Island until end of turn.

If I use this ability to change an opponent's land to an Island, then attack with a creature that has Islandwalk, would this mean that creature can't be blocked?

Yes, you can do this.  Islandwalk prevents a creature from being blocked as long as the defending player controls an Island1.  It doesn't matter whether that Island used to be a different kind of land - after using Tidal Warrior's ability, your opponent controls an Island1, and creatures with Islandwalk cannot be blocked.

1. Note that "controls an Island" means "controls a permanent that has the subtype 'Island.'"  The name of the card is irrelevant.

Not quite, it doesn't care about the land being an island, it cares about the land having the subtype island, there are 5 cycles of lands that are non basic but have subtypes, in addition to the two cycles of basic lands and type changing or replacing effects.

You are correct, but what I said is not incorrect.  A land with the subtype "Island" is an Island, just as a creature with the subtype "Goblin" is a Goblin.  However, I agree that it is worth clarifying the difference between the subtype and the name of the card.

Yes that is true, and all lands named island will have the subtype island, but for the sake of those coming to ask questions here, or find answers to questions that were already asked, it's worth being clear.

If my opponent controls an Island enchanted with Contaminated Ground, then according to the second sentence of this answer, my Merrow Harbinger will be unblockable because the card's name is still Island. That's incorrect though, for reasons others have already tried to point out.

@Rainbolt is right the answer still has some clarity issues, specify that being named island does not matter.

@Rainbolt No, that is not implied by the second sentence.  After playing Contaminated Ground, your land is no longer an Island.  It may be named Island, but it is not an Island.  Yes, that's confusing.  But I think that you're being more pedantic than is necessary to answer the question.

@Andrew I've already addressed that.

Not quite, you say that being typed an island matters but not that being named island doesn't. An island typed swamp like rainbolt suggests would not trigger islandwalk.

@BJMyers Don't focus on the exact question asked so much that you confuse people reading your answer. The goal is to allow not only the person asking the question to understand, but future readers, That's why my explanation goes on to give examples and an explanation of landwalk. If all we wanted to do was answer the question we only need one word, yes or no.

@Andrew In my opinion, you guys are making the answer way more confusing than it has to be by pulling in corner cases about dual lands, etc.  Nevertheless, I've edited my footnote to be as clear as possible while still scoping the answer to the question asked.

@BJMyers I withdraw my previous comment (but I won't delete it yet, so others can see the mistake I made). I wasn't trying to be pedantic about your choice of English words - I truly thought that the answer was using incorrect game terminology. I realized I was wrong when I found this rule that totally supports your answer: 109.2. If a spell or ability uses a description of an object that includes a card type or subtype, but doesn’t include the word “card,” “spell,” “source,” or “scheme,” it means a permanent of that card type or subtype on the battlefield.

Yes.
The land was granted the Island type, and Islandwalk checks the type of the card (not its name).

702.14c A creature with landwalk can’t be blocked as long as the defending player controls at least one land with the specified subtype (as in “islandwalk”), with the specified supertype (as in “legendary landwalk”), without the specified supertype (as in “nonbasic landwalk”), or with both the specified supertype and the specified subtype (as in “snow swampwalk”). (See rule 509, “Declare Blockers Step.”)

Incidentally, that also means you can tap it for blue mana.

305.6. The basic land types are Plains, Island, Swamp, Mountain, and Forest. If an object uses the words “basic land type,” it’s referring to one of these subtypes. A land with a basic land type has the intrinsic ability “{T}: Add [mana symbol] to your mana pool,” even if the text box doesn’t actually contain that text or the object has no text box. For Plains, [mana symbol] is {W}; for Islands, {U}; for Swamps, {B}; for Mountains, {R}; and for Forests, {G}. See rule 107.4a. See also rule 605, “Mana Abilities.”

Correct. Islandwalk, and any other landwalk ability doesn't care why the land meets the condition, only that it does, this means Islandwalk works on any land subtyped island including:

Original dual lands like Volcanic Island
Shock Lands like Breeding Pool
Battle Lands like Sunken Hollow
Cycling Dual Lands like Irrigated Farmland
Moonring Island
Snow-Covered Island
normal basic Islands
Lands under the effect of a type changing (replacement) effect (like Tidal Warrior)
Lands under the effect of a type changing (addition) effect (like Aquitect's Will)

Type changing of lands into islands was used heavily when Stormtide Leviathan was played, since the leviathan did the type changing, became unblockable, and prevented most other creatures from attacking.
Other types of landwalk exist, other than the walks for the basic land types like:

Legendary Landwalk (as seen on Ayumi, the Last Visitor)
Desertwalk (as seen on Desert Nomads)
Nonbasic Landwalk (as seen on Dryad Sophisticate)
Snow (basic)walk (as seen on Rime Dryad)
Snow Landwalk (as seen on Zombie Musher)
Denimwalk (only seen on Hurloon Wrangler and in the legends of Magic: the Gathering play, caused someone to respond to combat by taking off their pants. Also technically not a 'land'walk)

This is a very detailed explanation of Landwalk, but only the first 19 words address the question.


text:
How do I determine a character's probability to escape from combat in DungeonQuest (third edition)?
I have 4 cards with the following numbers on them: 1, 2, 3, 4.
My opponent has 4 cards with the following numbers on them: 2, 3, 4, 6.
We both randomly draw a card from our decks, if my number is equal to or higher than my opponent's I will escape successfully. What is my probability of escaping? Please show how you arrived at the proper answer. Thanks!

The decks here are small enough that we can explicitly list out all the possibilities:
your draw, opponent's draw
1, 2
1, 3
1, 4
1, 6
2, 2 *
2, 3
2, 4
2, 6
3, 2 *
3, 3 *
3, 4
3, 6
4, 2 *
4, 3 *
4, 4 *
4, 6

I've put an * next to all combinations which result in you escaping. As you can see there are 6 of those out of 16 total. Since each pair of draws in the list is equally likely, your probability of escaping is just 6/16 (which is 3/8 or 37.5%).
If you're trying to do this kind of calculation in the middle of a game (i.e. quickly and in your head), you may want to solve it slightly differently. First of all, we can tell that there will be 16 pairs in the list without actually listing them out, just by multiplying the deck sizes (4*4). After that you only have to count the ways to escape, which you can do by seeing how many cards each of yours beats: your 1 doesn't beat any (0), your 2 wins against their 2 (1), and so on for your 3 (2), and your 4 (3), for 0+1+2+3=6 ways of escaping.


text:
How does Hireling work with Throne Room or King's Court?
I was playing Dominion Adventures combined with Prosperity, the "Think Big" setup.
The main focus here are these 2 cards:

King's Court (from Prosperity)

Hireling (from Adventures)

Now the problem.
it's my turn and I have in my hand both of the cards above.
What happens if I play King's Court with Hireling?
My interpretation is that for the rest of the game, each turn, I draw 3 extra cards.
Can I get a confirmation or a correction on this?
Side notes:

The same scenario can happen if I play Throne Room from the base game and Hireling. (but with 2 instead of 3).

I've got this from the wiki page for the Hireling card:

And if you play a Necromancer that plays a Throne Room that plays a Hireling twice, the Necromancer will stay in play for the rest of the game.

The next logic step (my interpretation at least) from here would be that King's Court in my case, stays in play for the rest of the game, but again, I'm not sure since the rule above does not say that "Throne Room" stays in play, only Necromancer.

I did a bit of searching on the internet, and did not find anything definite about whether or not the Throne Room or King's Court stays in play.

it does stay in play. see the link in Zibelas answer

The wiki has this line on Hireling:

If you use Disciple (or a similar card, like Throne Room) to play
Hireling twice, you will draw two extra cards each turn, and Disciple
will also stay in play for the rest of the game.

Since King's Court is the big brother of Throne Room (same wording with just a better effect), from this we can infer that you do get 3 cards and that King's Court stays in play as well.

I'm glad I got the logic right, but I'm pissed off I didn't get to that wiki page line. Thanks for the confirmation.

"little brother" perhaps.

I tried using a Throne Room to play a Hireling twice on https://dominion.games/, and both the Throne Room and the Hireling stayed in play for the whole game.
That seems right to me. The Dominion Strategy wiki says "If you use Throne Room to play a Duration card, the Throne Room also stays in play until you discard the Duration card. This enables you to track the fact that the Duration card was played multiple times."


text:
What land destruction enabler was wrongfully banned in the early history of Magic: the Gathering?
I once heard a story about a Land Destruction deck that dominated tournaments at some point in early Magic's history. The story as I remember it is that the deck ran heavy land destruction to deny resources to the opponent, and it won with another card, which I believe dealt damage based on lands destroyed.
The card in question was inevitably banned, and Mark Rosewater occasionally comments that it's not the card's fault the deck was winning, and Land Destruction in general should have been seen as the problem instead.
What is the name of the card that was banned this way?

You may find this question interesting. https://boardgames.stackexchange.com/questions/28919/why-was-kird-ape-banned-in-very-first-extended-ban-list

Dingus Egg was banned once upon a time, and it does 2 damage to the land's controller when a land is put into the graveyard from play. A few of these do a lot of damage per land, I've seen it in a few land destruction decks over the years. It's not currently banned in any formats it would otherwise be legal in.

As a side note, I agree with MaRo, land destruction can get to be a big problem, thankfully it has slowed down over the years.

They really where clueless about bannings in the early days.

Then again that did share a format with both strip mine, sinkhole, and wasteland.

Strip mine was the one I was thinking of

@Segfault yes except the specific question asked for a card that "dealt damage based on lands destroyed." strip mine didn't to damage it just destroyed lands.

@NeilMeyer Clueless about banning in early days, now getting back to being clueless about design, there were years without a standard ban, now we're getting those regularly since Mindsculptor.

@NeilMeyer with strip mine and wasteland it's a double edged sword, sacrificing strip mine or wasteland to destroy an opponent land nets you both the same damage, both lands hit the graveyard, and you'd take the hit first (if losing that life would decide the game, or open you up to losing from burn spells cast in response)


text:
What's the "biggest change we've ever made" in Magic?
I'm currently catching up on Head Designer Mark Rosewater's "Drive to Work" podcast. I've been out of the loop for about a year.
In Episode 460: Announcements, which aired in August of 2017, he says:

"There is a big revamp in behind the scenes of how we make Magic. A
  big one. Like, probably the biggest we’ve had since I have worked at
  Wizards."

He goes on to say that he will write an article in the fall to announce it, and that it's "the biggest change we've ever made."
Well, fall has come and gone and I'm still clueless. I've perused MaRo's articles from August through now, but I still haven't found anything that indicates or announces any sort of major paradigm shift.
What is the big change MaRo is referring to? And, if possible, What articles/podcasts cover this announcement?

This was to do with Vision design (see podcast #495 and #496) and the introduction of the design play team. There's an article here where Maro talks about it from October of 2017.
It's a very interesting article and gives me high hopes for the future of Standard considering how much of an issue they've been having in terms of creating balanced and fun Constructed environments recently.

Checked both of these out and my question is answered. One thing, though: The Vision Design appears to also be discussed as early as #495 (Vision, Set, and Play Design)

Ah, my bad, I just flicked to the first podcast I saw Vision on as I knew it weas recent, I'll update my answer


text:
Can a spell fizzle because a cost-reducing effect is removed?
In this scenario, would my Aerial Responder fizzle because the mana cost is higher than I can pay?
I have a Ballyrush Banneret out on the battlefield, which says "Kithkin spells and Soldier spells you play cost {1} less to play."
I play Aerial Responder for WW, tapping my only two plains.
In response to this, my opponent casts Lightning Bolt on Ballyrush Banneret.
We begin to resolve the stack, and first of all, Lightning Bolt kills Ballyrush Banneret.
Now Aerial Responder is going to be resolved. Does it still only cost WW, or does it now cost 1WW? Would it fizzle? If instead of only having two plains when I cast Aerial Responder I actually had 3, could I tap the final plains in response to this so that Aerial Responder could be cast?

maybe also good to know: the term fizzle is as far as I know only used if a spell gets countered because all of its targets are gone. If a spell gets countered by any other rule, or other way, you wouldn't call it fizzle

@IvoBeckers I think fizzle is used to describe any state based countering of a spell, which would be the case here if the cost changing after the spell was on stack mattered. In reality the only time we really see state based countering is due to lack of targets.

No, a spell can never fizzle because you're unable to pay the cost.
Among the steps involved in casting a spell are the following:

you announce that you're casting the spell
you determine what it costs
you pay the cost that was previously determined1

These steps (and a few others) occur immediately back to back; your opponent can't do things between them. The whole process of casting a spell is one "block" of actions that can't be interrupted. Once the "block" finishes, the spell is considered paid for. Period. If the spell's cost were somehow to change later, that doesn't matter; all that matters is that you paid the cost that was required at the time you cast the spell.
Even if you find yourself unable to pay the cost of a spell during the casting of the spell (i.e. at the third bullet point), the spell does not fizzle. Instead, you back the game up to before you started casting the spell in the first place (unless you are using Selvala, Explorer Returned, then you call a judge and watch them cry).
There are some effects, for example Mana Leak and Frost Titan, which counter a spell unless its caster pays a certain amount of mana (or takes some other action, e.g. Reality Smasher). It's important to note that these do not change the casting cost of the spell, and even if they did, it wouldn't matter because the spell has already been paid for. What Mana Leak does is create an entirely separate cost, which has to be paid at the time that Mana Leak resolves, long after the spell has been cast.

1In rare circumstances the action of paying the cost can change what the cost would be, but it doesn't change the amount you actually have to pay. For example, suppose you wanted to cast a Soldier spell costing {1}{B}{B} that said "As an additional cost to cast [this], sacrifice a creature", and you have Ballyrush Banneret in play. You would first determine the cost you need to pay, which is {B}{B} and sacrificing a creature. That gets "locked in" before you start paying it. So you can safely sacrifice Ballyrush Banneret, and it doesn't mean you have to pay any more mana.

While this is clearly the correct answer, it might be improved by making mention of counterspells like Mana Leak?

@Cronax Could you elaborate on how you think that would improve the answer? I've written this with the view that a counterspell or anything else that might happen after the casting is "committed" doesn't matter, and I avoided mentioning more factors than necessary so as not to complicate the answer.

Maybe a note at the end about how the mana leak cost is different somehow?

You claim it doesn't change because nothing can happen between determining the cost and paying it, but paying the cost itself could change the cost. (For example, the cost could include both sacrificing a creature you control and paying an amount of mana based on the number of creatures you control.) The actual reason is that the cost becomes locked in in the cost-determining step (601.2f).

Why would we need to mention Mana Leak? It doesn't have any special interaction here that I can see -- it just works like an ordinary Mana Leak.

@ikegami Yes, I intentionally didn't mention rare corner cases like that for clarity. But I could edit in a note.

Mana Leak and all other soft counters don't change the cost of the spell, they are just spell that counter but gives the controller a way to prevent the countering.

@DavidZ I think that exactly the facts that Andrew mentions would add value to the answer as a "while nothing can change the cost afterwards, there are situations where you do have to pay more to actually get the spell's effect, like for instance when counters like Mana Leak are used". It feels like this would make the answer more complete, although I do understand the risk of going to far with elaboration.

@Cronax I guess it just doesn't make sense to me how having to pay more to actually get the spell's effect would seem to have anything to do with the spell's cost. But I could add a note to clarify this for others. Let me think about how to phrase it.

@doppelgreener I don't like the phrasing of that edit. I will make an edit that incorporates information from the comments, but as I said, I'm thinking about how to phrase it in a way that retains the important characteristics of how I wrote it in the first place.

@DavidZ Fair, but I think it's important to find a way to incorporate that the cost is "locked in" after determination and before payment (that's even the term the rules use) so as to intuitively help people understand what happens if I sacrifice a Goblin Electromancer to Altar's Reap. (It still costs 1 less)

@doppelgreener Sure, I'll definitely mention that, but I actually don't think it's quite that important. As I understand it the question is focusing on cost changes that would be caused by spells (or abilities) that are played in response. The possibility of the cost changing between when it's determined and when it's paid, within casting of the spell, is a somewhat different situation which I'd rather keep out of the main explanation to avoid distraction.

No reason to cry over Selvala - her effect is still resolved, everything else is reversed -
If you activate Selvala’s ability while casting a spell, and you discover you can’t produce enough mana to pay that spell’s costs, the spell is reversed. The spell returns to whatever zone you were casting it from. You may reverse other mana abilities you activated while casting the spell, but Selvala’s ability can’t be reversed. Whatever mana that ability produced will be in your mana pool and each player will have drawn a card.

Casting a spell involves putting it onto the stack and not much else, but one of those things is that you pay the cost to cast that spell. Since you've already payed the cost to cast Aerial Responder before Lightning Bolt can be cast, what it does when it resolves doesn't matter. Your new creature will resolve regardless of whether you're able to produce another mana.

Like stated in the other answer your Aerial Responder is already on the stack. The cost was reduced when you cast it fulfilling the requirements for it to be cast. The Lightning bolt would then kill the Ballyrush Banneret but your creature spell will still resolve and hit the battlefield.
As for the second question, If you happened to have the 3 lands, this would not matter, what is important is that you have the manna to cast a spell. if the cost of the spell is reduced, after you cast it, nothing can increase the cost of the card directly (there exists cards that counter spells unless the controller pays"X")