[Kormar the Wanderer]

Yup. If you can't handle fighting them, the best thing to do is get everyone except for your thief by the exit to the next level, then have your thief pick the lock and loot the items and haul arse back to his friends before the dwarven doomguards can catch him. Ironically, though, if you can manage to get them seperated, they are much easier to deal with than when they attack as a group...