All the potential to abuse this card is in the turn that it is played, forcing OP to dump his whole hand. Multi-turn doesn't really matter at all.
It is quite easy to abuse. This + silence for example. Its cost must be too high to play on the first turn. I think 6
. Personally, I think something like this would be more fun:
permanent, casting cost 2
. Maximum hand size of both players is reduced by 2.