Grave Servitude is a common Enchantment — Aura card from Mirage (MIR), collector number 126. Current market price: $0.12, TCGplayer market prices via Scryfall.
You may cast this spell as though it had flash. 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. Enchant creature Enchanted creature gets +3/-1 and is black.