It doesnt seem very effective, but maybe its because i dont have 0% cost. Thoughts?

Get it to 0 cost, take the Impact perk and perma-stagger everything in sight. It'll take you longer to take enemies out than if you were slashing them with a sword, but it'll work. Or, if you're on PC, get one of the many mods that tweak the magic system to make it better and more effective without having to resort to cheesy exploits.