Case of the Burning Masks (Murders at Karlov Manor 113) - Uncommon Magic: The Gathering Card

When this Case enters, it deals 3 damage to target creature an opponent controls.
To solve — Three or more sources you controlled dealt damage this turn. (If unsolved, solve at the beginning of your end step.)
Solved — Sacrifice this Case: Exile the top three cards of your library. Choose one of them. You may play that card this turn.