I've never had a problem with hit-or-die spells. On all the tough battles they just don't work; at least not without debuffs. At least, that has been my experience.
I hope summons have some kind of distance from caster limit. In BG you can really abuse summons to do most of the fighting for you. Just scout with invisibility and then send a hord of skeletons/skeleton-warriors to pwn the monsters. Seemed a little cheesy.