To kick it up a notch, make them stand on a half-court together, and have to whip the sphere off of a wall of force, aiming to hit the other caster on the rebound. Magical Squash.
I admit, i cribbed it from The Dresden Files. Admittedly, in the book, it was a chunk or mordite (which is functionally a sphere of annihilation anyway), but I thought a nonlethal version would be appropriate.
Last edited by digiman619; 2016-08-25 at 11:52 PM.