I'd wondered about this. Previously, I played Unstoppable Chop against two enemies, one of whom Blocked. This triggered the "take it back into your hand instead of discarding it" option on the attack. Thus, I could kill people yet again with a partially-Blocked attack. I don't know if that's wise (this two-target card might be a funny one to trust with the special "back into hand" rule), and it seems like it risks errors. Specifically, just now I did the same thing (facing Gary in multiplayer) and the game has frozen right before the "go back into your hand" stage. All damage has resolved and I'm sitting here with no other text nor a chop in hand. This might matter: the first time, the person who Blocked was the second in the two-target chop resolution; this time, the person who Blocked was the first to resolve.
Tested both cases (first target blocks and second target blocks) and can't repro the freeze. Has anyone else seen this?
I use the card on my priest and have seen no issues. Though it's hard to get two enemies close to my priest in PvP