Antoine's actions during activation of his Cryptbreaker seems pretty clear that he intended to activate the second ability, so I would treat this as a GPE - GRV, by failing to pay the correct cost for the ability.
The fix is more difficult.
Option A (the fix I think is the correct answer): Entirely back up the activation by placing a card from Antoine's hand onto the top of the library (Nancy will choose which one), putting him back up one life, and untapping the swamps and the Cryptbreaker. Antoine can choose to activate the ability now, but is not required to.
Option B (the fix I'd much rather use but I don't think it fitsanywhere in the IPG): Antoine's ability has already resolved, and we will leave it that way – no revealing his hand to Nancy. However, we will require that he pay the correct cost by simply untapping the two swamps and tapping the other two Cryptbreakers. In other words, we back up the activation but then re-activate the ability by paying the correct cost.
Option C (the fix I think is technically correct but not the best choice here): Leave the game state as-is, no backup.
This situation – incorrect casting/activation costs – has been a big concern for me since I first started judging! I REALLY want Option B to be a partial fix in the IPG, but I don't see it. This same issue arose with the “It's Plain to See” scenario (
https://apps.magicjudges.org/forum/topic/34340/ ), and I really disliked the solution although I understand that it is official. Why can't we simply partial-fix the incorrect tapping of mana, rather than backing up through the entire activation? Instead, we have to back up the entire ability, including the scry/draw, and then afterwards we don't even require the player to activate or cast correctly?
In short, I wish there were a partial fix for incorrectly paying casting costs or activation costs. Maybe I'm missing something…I think I'm going to create a discussion in the Competitive REL forum so we can discuss it further.
Edited April Miller (June 14, 2017 12:36:53 PM)