RulingRules Reference 1.7

If Assault causes the villain to attack me and there is only one card left in the encounter deck, is Assault in the…

Question

If Assault causes the villain to attack me and there is only one card left in the encounter deck, is Assault in the encounter discard pile when the discard pile is shuffled into the encounter deck after the villain is given a boost card?

Answer

No. Assault is not discarded until it finishes resolving, which happens when the villain’s attack has been resolved.

— Rules Reference 1.7