Necromancer's Covenant is a rare Enchantment card from Alara Reborn (ARB), collector number 82. Current market price: $0.75 (foil $3.13), TCGplayer market prices via Scryfall.
When this enchantment enters, exile all creature cards from target player's graveyard, then create a 2/2 black Zombie creature token for each card exiled this way. Zombies you control have lifelink.