Case of the Uneaten Feast is a rare Enchantment — Case card from Murders at Karlov Manor Promos (PMKM), collector number 10p. Current market price: $1.29 (foil $3.39), TCGplayer market prices via Scryfall.
Whenever a creature you control enters, you gain 1 life. To solve — You've gained 5 or more life this turn. (If unsolved, solve at the beginning of your end step.) Solved — Sacrifice this Case: Creature cards in your graveyard gain "You may cast this card from your graveyard" until end of turn.