The battle with Kethric is one such battle.
The first time I fought him downstairs...
I used everything I had. Surprise! He was just the warm up! Exactly as designed, well done!
There I stood, casters on empty, me, a fighter with that purple-red halberd, and Whiffmistress Lae'zel.
No knowledge of any of this:
1. Use Doomhammer, or at least those arrows that do the same thing.
2. No knowleldge the little bulges in the circle were outside his no-heal aura radius.
3. Potions of hill giant strength
Soon even severe savescumming could not do the trick. Even if he missed he still did some damage and I was out of heal potions, not farming those, either, no haste scroll, nothing.
The solution was to drop the difficulty down mid-fight, which worked, but golly, bards won't be singing about my effort any time soon!