I'd like to put in a vote for Storm Call. There's nothing like calling the elements to your aid. Of course, as a downside, you now have to fight in the rain, too. Best part? When the lightning only hits your enemies. Helps soften 'em up for the finishing touch.
Worst part? Can't use it inside a building, dungeon, cave, etc. Which is totally missing the point, imo. Can you imagine the props coming your way when a Force 8 gale (with lightning) starts drenching Dragonsreach?!
Your character would be like:
That's right, muthaf******! Bow down to The Mastah!
'Course, now I'd probably have to
swim outta the cave instead of
walking out of the cave.