Graven Archfiend 
Artifact Creature — Gargoyle Demon
As an additional cost to cast this spell, you may sacrifice a non-Demon creature. Flying When Graven Archfiend enters the battlefield, if its additional cost was paid, conjure a card named Demonic Pact onto the battlefield.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyNOT LEGALvintageNOT LEGALcommanderNOT LEGAL