You may cast Necromancy as though it had flash (You may cast this spell any time you could cast an instant.). If you cast it any time a sorcery couldn't have been cast, the controller of the permanent it becomes sacrifices it at the beginning of the next cleanup step. When Necromancy enters the battlefield, if it's on the battlefield, it becomes an Aura with "enchant creature put onto the battlefield with Necromancy (Target a(n) creature put onto the battlefield with Necromancy as you cast this object. This card enters attached to that creature put onto the battlefield with Necromancy.)." Put target creature card from a graveyard onto the battlefield under your control and attach Necromancy to it. When Necromancy leaves the battlefield, that creature's controller sacrifices it.