The Ace of Spades

Hexproof, Convoke
When The Ace of Spades enters, search your library for a legendary spell. You may place it onto the battlefield. If you do not, place it into your hand.
{w}{u}{b}{r}{g}: Exile The Ace of Spades, then return him to the battlefield.

"I've never seen it's face. Not even once. If you're lucky, you won't either."
—Unknown Eidolonian Gambler