Master of Predicaments is a rare Creature — Sphinx card from Magic 2015 (M15), collector number 67. Current market price: $0.60 (foil $1.79), TCGplayer market prices via Scryfall.
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.