Dallis won't die.
I killed Dallis (she was a chicken for 2 turns, un-chickened, i killed her), she was at 0 health. Nothing happened.
I stunned her, did more damage, her turn comes around, still at 0 health, nothing happens.
Go another round, Alexander just disappears (guessing the script half worked, and he left, but no dialogue or anything happened). Dallis, at 0 health, gets to her turn, suddenly as 54 health, kills a party member, starts to walk away.
I use spells - no CC/debuffs do anything (burning, cold, freezing, slow). Her turn comes around, gains a ton of health (0 -> ~115), keeps walking away. I get her to 0 health again, disarm her, turn her into a chicken, still nothing, she won't die, she won't transform and do the scripted exit, nothing.
Also, my totems just gave up on targeting her, even before she was dead, just at some point they stopped caring.