Some act 4 boss fights (in particular, S22B and S23B) are unsolvable without debug mode according to @nemaara. This is a bad thing.
Relevant IRC log excerpts:
20:47:38 <nemaara> also, in the second battle with Elyssa, it's basically impossible to kill her
20:48:02 <nemaara> because you can't kill her in a single turn with the union and when she retaliats
20:48:16 <nemaara> whoever she hits doesn't use the union attack, so she regains all her HP
20:48:23 <nemaara> well I mean attacks on her turn
...
21:32:34 <nemaara> also, it's basically impossible to kill Argan with Elynia alone, but you have to kill him at least once with her before Mal Keshar comes back
Some act 4 boss fights (in particular, S22B and S23B) are unsolvable without debug mode according to @nemaara. This is a bad thing.
Relevant IRC log excerpts: