The Creation of Avacyn is a uncommon Enchantment — Saga card from Modern Horizons 3 (MH3), collector number 86. Current market price: $0.26 (foil $0.34), TCGplayer market prices via Scryfall.
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.) I — Search your library for a card, exile it face down, then shuffle. II — Turn the exiled card face up. If it's a creature card, you lose life equal to its mana value. III — You may put the exiled card onto the battlefield if it's a creature card. If you don't put it onto the battlefield, put it into its owner's hand.