Necromancer's Covenant is a rare Enchantment card from Commander 2015 (C15), collector number 229. Current market price: $5.52, 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.