SPOILER
And there are two more fight to come. I was lucky and got three call of Nature spells which made he fight against Ahriman do-able - I only lost one berserker and might have been better in case I got snakes instead of 2x hyenas. But I'm quite sure you cannot win the next two battles without casualties (and I'm also quite sure someone will prove me wrong sooner or later
), so I said good-bye to a no-loss game for now.