Ghoulcaller's Harvest is a rare Sorcery card from Innistrad: Double Feature (DBL), collector number 225. Current market price: $0.34 (foil $0.86), TCGplayer market prices via Scryfall.
Create X 2/2 black Zombie creature tokens with decayed, where X is half the number of creature cards in your graveyard, rounded up. (A creature with decayed can't block. When it attacks, sacrifice it at end of combat.) Flashback {3}{B}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)