Paradoxacles, Chaos Form

Tribute 3 (This creature cannot be cast except by sacrificing 3 creatures you control.)
Whenever you cast a spell exile the top card of your library, if it has a converted mana cost equal to or less than cast spell you may negate it, if you do cast the exiled card without paying its mana cost.
This creatures powers and toughness are equal to the number of cards you own in exile.