Are people actually beating the fight where the cultist leader teleports away, or do you just agree to work for him? I don't see how it's possible, but then I didn't see how the second fight of the game was possible with my first party so it could just be a failure of munchkinism.
Not that I'll be playing any more for the foreseeable future, this thing crashes if you breathe too heavily.
Id di it with a party of melee , paladin, barbarian, fighter (centaur) ,gladiator (mantis) one rogue one bard . Rogue has improved iniative, dex 20 etc . First turns, use the confusion scroll with the rogue, kill the hag at the bottom first, then kill casters , get lucky and fight is won.Outcome is same , he telports you away without your equipement.