What is a mistrigger?
Asked by acedev 2 weeks agoMy friend is confused on Niblis of Frost's ability. After he casted a vapor snag on his opponent's token, he placed a land and then entered combat. He thinks that since it doesn't say may, it must happen even after the missed affect passed. Would the effect still trigger even though he didn't declare Niblis's effect prior to combat? He also mentioned pact of negation and how that would work if that mistriggers.
There is no such thing as a "mistrigger", it is possible during games to forget that triggered abilities occur, but that is a mistake, (an update on that matter is here) http://magic.wizards.com/en/articles/archive/missed-trigger-update-2013-02-04
However, on to what you wanted to know, since you cast Vapor Snag targeting an opponent's creature, the spell goes onto the "stack", since you have cast an instant or sorcery spell, Niblis of Frost's effect will go onto the stack as well, and happens before your Vapor Snag even resolves.
This means that the controller of the Niblis would tap target creature, and then the vapor snag would happen, and in that order. If your opponent controls no creatures when Niblis's effect is activated (however there must a target in this situation otherwise you aren't targeting a token with Vapor Snag), the ability would fizzle and do nothing, however if there is a legal target, then it must be tapped. Your friend cannot say during combat, "oh yea, now I'll tap that creature" because that's not how the card works.
March 12, 2017 9:52 p.m.
The term is "missed trigger". If the controller of a triggered ability doesn't acknowledge it at the point it would first affect the game then it's considered to have been "missed". The Magic Tournament Rules handle different types of missed triggers in different ways. Because Niblis of Frost's last ability has a target, it has to be acknowledged at the time it would first be put onto the stack. If the player takes another action after that point without naming a target first then the trigger has been missed. Like TeamSDBags said, in this example that would be before Vapor Snag starts to resolve. If your friend missed the trigger for Niblis of Frost's last ability but remembered it later, then the Judge would give your friend's opponent the choice of whether or not to add the trigger to the stack now.
Pact of Negation's trigger has a default action associated with a choice the player is supposed to make (i.e. lose the game unless you pay ). If that trigger is missed and then remembered later, the Judge would give the player's opponent the choice of whether or not to resolve the trigger's default option ("lose the game") now.
It's worthwhile to note (and this may be part of where your friend is getting confused) that the trigger from Niblis of Frost's Prowess ability doesn't need to be acknowledged until either combat damage is being dealt or some other effect tries to use its P/T to calculate something. The +1/+1 granted by Prowess affects the game in a non-visible way, and a trigger like that just has to be acknowledged at the first moment it would have a visible impact on the game state.