Help please

I found a fairly easy and somewhat honest way to deal with the demons. They pick one person to whup on until they are dead, (after they uncork some of their spells, afraid just sucks)then switch to another. I just ran my toughest fighter up to Balor, cast otiluke's resilient sphere on the fighter and Balor just futilely flailed on the invulnerable fighter while Scorpp opened a can of whuppen beans on him from a distance with the frostbrand. A couple people were unconcious when he died (this was the first time I faced him) but he fell after the afraid wore off. This works for a lot of battles, just see what character is getting ganged, then cast otiluke on him. Not being able to use one character during battle is a small price to pay.