Neat! Took me a while to figure out how to play. For future players:
Click and hold on the wizard, then drag down and to the left to aim. Release to throw.
I still can't figure out what "click anywhere on the screen after throwing the ice/thunder spell to use its ability" means (it doesn't seem to change the behavior whether I click after throwing or not, even on Level 2). And I wasn't able to get past level 2, but I can imagine that if you're clever enough, you can arc it to take out two enemies with one throw. I might come back and work on that later.
All in all a very cute game!