Grease has a small area affect, but it also doesn't require concentration. Sleep is great for groups of kobolds and small groups of goblins, but is little use against orcs unless you beat them down first. And again, Sleep is not concentration. Make sure you make use of the few non-concentration buffs and controlling effects, as combat gets a bit boring otherwise. As an Evoker, you can make the most of the school's instantaneous effects. Due to the Great Concentration Plague, Sculpt Spell seems untouchable when compared to the other arcane traditions.