So this just happened.
I went from Klaw I to Klaw II. I searched my encounter and discard for the "immortal" klaw and it was nowhere to be found.
Turns out, just before defeating Klaw I, i cycled my deck with tony stark ability and drew an encounter card. Guess which one it is?
So, its neither in encounter nor discard pile, so it just doesnt happen until the encounter phase? Until then Klaw II is just 10HPs less for now?