Altar of Bone 
Sorcery
As an additional cost to cast this spell, sacrifice a creature. Search your library for a creature card, reveal it, put it into your hand, then shuffle.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL