Master of Predicaments

Flying Whenever this creature deals combat damage to a player, choose a card in your hand. That player guesses whether the card's mana value is greater than 4. If the player guessed wrong, you may cast the card without paying its mana cost.

From Magic: The Gathering.

Open the interactive version on https://mythscribe.cloud/app/tcg/cards/cms6opjinisgjpb1huqo5iraz.