I’m not sure if this is a bug, but it’s definitely not supposed to happen. When running the tower, I came across an undead team with zomm in it. I took it out all except for zomm in the first turn and zomm spawned 3 zomminions. I then killed zomm but before I could finish off any of the zomminions, I lost. Looking back on the tower screen, I saw that all 3 of the non-zomm heroes were displayed at full health while zomm was displayed as dead, and of course started to get a little angry, as I killed all those heroes already. When I went to do that floor, however, all I found was zomm lying on the ground dead, sinking into the ground (like all the dead corpse animations do) and then giving me the prize straightaway.
I’m not sure this is supposed to happen. The game saves pontifex mortis’s undead form when in the tower, so I think it should also save zomminions (in the opponent’s case)