[The Hierophant]

Here's what I did:
Basically, you want to exploit the game's limited AI as much as possible.
I was in the 'exposed the doppelgangers and fought 2 Dragons at once' scenario.
Now, when outside the cave beef yourself up with your favourite power-up routine (I like bless, remove fear, mass protection from evil, emotion rage and hope, with Ilmater's fortitude and Tempus' strength to top it off). Run on into the cave, concentrate all attacks on one of the dragons, bring his ass down (getting your magic user(s) to launch a continuous stream of fireballs helps alot here). Now, here comes the cheesy bit, run back outside once one or two of your enemies are dead, the remaining enemies won't follow you out. Once outside rest up and repeat the process 'till they're all history. Killing nature's beautiful creatures in the name of second-rate civilization is such delightful fun.