Twincast

[Nazdakka]

From today's Ask the Judge:

Q: I saw a combo with Circu, Dimir Lobotomist and Twincast. It went like this: they played a Brainstorm while Circu was in play, copied it with Twincast, and then played another Twincast and copied the first Twincast, and then copied the other Twincast and so on, until the target library was removed. Circu says, "Whenever you play a Blue spell, remove..." Do the copies of the Twincasts activate Circu's ability, or do you have to play the spell from your hand?

A: That does not work. Circu's abilities trigger when a Black or Blue spell is played. These abilities do not trigger when a copy of a Blue spell is put on the stack. In this example, Circu's ability will trigger just three times—for the Brainstorm and the two Twincast that are played. You don't necessarily need to play a Black or Blue spell from your hand to trigger these abilities, but you do need to actually play a spell, and not just put a copy on the stack.

Can the 2*Twincast play described in the question above be used to produce a drawn game? I'm thinking that the answer is 'no', because if a loop is produced where there are choices to be taken which could end it, you just choose a number, X, of times for the loop to go round, and then you have to do something else.

Am I correct?

[Limbo]

Yes you are. Nothing changes in the gamestate, so the player controlling the Twincast just says : "I would like to Twincast Twincast googolplex" times. If the opponent does not want to interfere, the "loop" is resolved in a second instead of in a gazilion hours.

[Jacob Orlove]

421. Handling “Infinite� Loops

421.1. Occasionally the game can get into a state in which a set of actions could be repeated forever. These rules (sometimes called the “infinity rules�) govern how to break such loops.

421.2. If the loop contains one or more optional actions and one player controls them all, that player chooses a number. The loop is treated as repeating that many times or until another player intervenes, whichever comes first.

421.3. If a loop contains optional actions controlled by two players and actions by both of those players are required to continue the loop, the first player (or the first involved player after the active player in turn order) chooses a number. The other player then has two choices. He or she can choose a lower number, in which case the loop continues that number of times plus whatever fraction is necessary for the active player to “have the last word.� Or he or she can agree to the number the first player chose, in which case the loop continues that number of times plus whatever fraction is necessary for the second player to “have the last word.� (Note that either fraction may be zero.) This sequence of choices is extended to all applicable players if there are more than two players involved.
Example: In a two-player game, one player controls a creature with the ability “{0}: [This creature] gains flying,� and another player controls a permanent with the ability “{0}: Target creature loses flying.� The “infinity rule� ensures that regardless of which player initiated the gain/lose flying ability, the nonactive player will always have the final choice and therefore be able to determine whether the creature has flying. (Note that this assumes that the first player attempted to give the creature flying at least once.)

421.4. If the loop contains only mandatory actions, the game ends in a draw. (See rule 102.6.)

421.5. If the loop contains optional actions controlled by different players and these actions don’t depend on one another, the active player chooses a number. In APNAP order, the nonactive players can each either agree to that number or choose a higher number. Note that this rule applies even if the actions could exist in separate loops rather than in a single loop.

In your example, you control the loop, so it is infinite, but not a draw.

[Anusien]

However, you can cast a spell, play Twincast on the spell, twincast the twincast, misdirect the first twincast to the second, counter the original spell and the game draws.

[Jacob Orlove]

However, you can cast a spell, play Twincast on the spell, twincast the twincast, misdirect the first twincast to the second, counter the original spell and the game draws.

Wrong. Changing the target of a Twincast is an optional, player controlled effect. If you don't change it, the loop ends with Twincasts being countered on resolution because their targets are gone. Thus, while you can loop this as many times as you want, you cannot use it to force a draw.

[forests failed you]

It is also worth noting that putting a copy of target spell on the stack is not the same as casting a copy of that spell yourself.  For instance, because if its wording Twincasting a Tendrils of Agony does not allow you to put storm copies on the stack.

[rvs]

It is also worth noting that putting a copy of target spell on the stack is not the same as casting a copy of that spell yourself.  For instance, because if its wording Twincasting a Tendrils of Agony does not allow you to put storm copies on the stack.

Actually, that just doesn't work because of the way Storm works. Right?

[Jacob Orlove]

It is also worth noting that putting a copy of target spell on the stack is not the same as casting a copy of that spell yourself.  For instance, because if its wording Twincasting a Tendrils of Agony does not allow you to put storm copies on the stack.

Actually, that just doesn't work because of the way Storm works. Right?

No, there are other cases where it matters. For example, Twincasting your opponent's spell under an Arcane Lab will still give you a copy, because the copy is not played.