Command the Scourge

When Command the Scourge enters the battlefield, it becomes an aura with enchant
creature. Return target creature from a graveyard
to the battlefield under your control then attach Command the Scourge to it. When Command
the Scourge leaves the battlefield, sacrifice the enchanted creature.
{w}{u}{b}: Return Command the Scourge to its
owner's hand. Target opponent puts the top
three cards of their library into their graveyard.