[Zarr]

You can do this fight straight out of Irencius dungeon if you want I managed to do it. Here's how- First I told them I'd leave which is important because it gives you time to prepare, next I had Yoshimo set traps(special snare) at the Dwarf with the warhammer. This dwarf is a very good fighter and will cause you alot of problems but Yoshimos special snare can cause hold person on the victim. After setting the traps I hasted my fighters and moved Yoshimo in a position to backstab the mage. I then backstabed him killing him. Everyone then went hostile and the traps triggered causing hold person on the dwarf. I then had my fighters take on the imp which can use alot of nasty mind spells on your party if you don't kill it quick. Once the imp was dead I attacked the thief who then ran away. Then I killed the Barbarian who was a wimp. Now I switched my attentions to the dwarf who was still held. My hasted characters killed him before the hold spell ran out.

Overall I'd say the important things about this fight are:
1)Disabling the dwarf- he will cut your fighters down if you don't if you don't have Yoshimo you can always cast the third level cleric spell hold person (as Sazerac mentioned)
2)Killing the magic users FAST- the mage and imp will cast alot of nasty spells if you don't and you probably don't have chaotic commands at this stage to counteract the mind spells they use.

This just about somes up how I beat them, I hope this helps and good luck!