Even if you just stand near one of the regeneration chambers, that will be the one he goes for when his health gets down; if you temporarily deactivate that one using the nearby lever (or block his path with your creature, summons and/or his summoned walking armours), he should not be able to make it to the other chamber (Rush Attack, a bow or magic should be able to finish him off).
General Raze how defeated?He is about level 29, IIRC, so it wouldn't hurt if you went elsewhere to go up another level or two.
Have you finished off Stone's Flying fortress? If you've cleared a few caves near the start of the fjords, and the path through to High Hall and the harbour, etc, Stone's fortress (north east end of the long island in the middle of the channel to the harbour) would be the next logical place to go; I entered at about level 24/25 and made it to level 29 just before the end.
