Hey, love the game so far! Just wanted to mention that the bug brought up by LaceWolf a few days ago seems to still be present in the latest version. The zero health counter popped up once the first time I tried the battle, and hasn't shown up at all on retires of the bossfight for me. (And yes, I'm sure I did the patch correctly, the overlap points show up in the menu and everything).
The only things I can think of is either that the health regen fires before the check to see if he's at zero hp, meaning the check never succeeds, or it has something to do with having the Fairy subclass equipped. Maybe the Unpredictable skill overrides whatever is happening between turns?
Like I said though, love the game, can't wait for more!