What if instead of adding an arcanyst to your hand, it turned a random card in your hand into a random arcanyst? Or a random arcanyst in your hand into a random arcanyst?
This would:
Take out the card draw. You need a hand for it to work.
Introduce a risk/reward aspect. You have to judge if it will improve your hand at all. If your hand is just an illusion, go nuts. If you have a good card in your hand, you should probably play it first. It also means as you cast more spells, playing more spells gets riskier.
I think making it turn a random arcanyst in your hand into a random arcanyst is the better of the two.