I'm using 33.6 and I'm having trouble dealing with Kangaxx again. In the past I keep running into a bug where Kangaxx won't die and transform. I used to think it was because of Protection from Undead scrolls, but it happens even when I don't use them at all, on any party members. I'll Breach him early on (I have multiple arcane spellcasters and the difficulty is on Tactical) and then quickly bring him down to Near Death, but he keeps on casting spells, even if they get disrupted over and over again. Even healing him and bringing him back down to Near Death won't trigger his transformation.
EDIT: I managed to get around it by changing his script so that it checks to see if he's at less than 10 HP, instead of exactly at 1 HP. Maybe the larger window is necessary given his regeneration from the ring. I had to spawn a new version of him, though; creatures can't be changed by Near Infinity in a save game if they were already loaded before the change. It's a simple preventative measure, but otherwise it seems Kangaxx is just randomly immortal.