Either the Winter Guard or the Soviet Super-Soldiers -- or maybe there will be an ATA that both the keywords can use.
I can't imagine the Asgardians needing an ATA, though, especially if it had come out in HOT -- what additional power would they have needed?
Any figure using this ATA gains a +3 attack, +3 defense, and +3 damage. If the player controlling the figure using this ATA speaks some bastardized Marvel "Old English," such as "Yea, verily," or "Have at thee", the player can as a free action KO any figure on the opponent's force. Deal this figure one unavoidable damage, then, at the end of this turn, heal this figure two clicks and remove all action tokens.
No raccoons or tree creatures were harmed during the making of this film.