Tzeentch, Lord of Entropy

Flying, ward {x} - X is the mana value of the top nonland card in your graveyard

{1}{u}{b}, {t}{ut}{t}: each opponent mills five cards, you may cast instants and sorceries milled this way, this turn, using mana of any color

Tzeentch's power and Toughness is equal to the number of instants and sorceries in each players graveyard

When Tzeentch dies, return it to the battlefield tapped and transformed under its owner’s control.