Specifically the Wizard promotion in Mist / Bootleg Bay and the Cavalier promotion in Free Haven. For the first one you'll probably want to have Water Walk and someone with at least a couple of points in Water magic. There are some others also, but those two should get you up some levels and give you a better shot at the Temple of Baa, which is tough at any level.
For the specific problem you mentioned, I've found that Ring of Fire can be very helpful. I just squeeze into one corner in that room, fight off whatever happens to come in and then cast Ring when all the other mobs gather round.
What's the make-up of your party?
