Nicol Bolas, Tamer of Eternity

Devoid (This card has no color.)
Flying, Trample
When you cast this spell or a colorless spell, you
may pay {x}. If you do, target player discards X cards, then you sacrifice half X permanents rounded down.
When Nicol Bolas, Tamer of Eternity is put into a graveyard from the battlefield, its owner shuffles their graveyard into their library.