Indeed! It affects not only combat though. I hope there will be a huge spider again, I loved the spider in DOS. It creeped me out for being very much a spider while saving my bacon more than once
I mean, it's extremely useful to have a summon you can send into areas you don't want to go your self. A stream of lava would be no match for a fire elemantal... Just imagine the puzzles you could create based on summoning.
