Prodigy Crystal

Exile all creatures you control.
At the start of your turn return one of your creatures exiled by this card into play, it's power and toughness are now 1/1 instead. (Repeat this for all of your turns, but everytime a creature enters play from exile, double its power and toughness from the last creature, i.e if a 1/1 was played last, the new creature is 2/2, after that will be a 4/4, and so on.)
"It will make your kin stronger. You? Not so much."