Master of Predicaments 67 (Magic 2015 (M15))

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.

NM - $1.50
LP - $1.50
MP - $1.50
HP - $1.50
DMG - $1.50