Yorevhel, Chaos Wielder

Flying
Whenever a player casts a spell from their hand,
you may choose whether or not to exile that
spell. If that spell is exiled, it's controller exiles
cards from the top of their library until they
exile a card that shares a card type with it. That
player may cast that card without paying it's
mana cost. Then, that player puts all of the cards
exiled with this ability on the bottom of their
library in a random order.