John Kramer, Jigsaw

Skulk (A creature with skulk can't be blocked by creatures with greater power.)
When John Kramer attacks, choose a card in your
hand. Defending player guesses what card type
that card is. Reveal the card. If they guessed correctly, they lose 3 life and you discard that
card. If they guessed incorrectly, they sacrifice a creature with the highest power among creatures
they control.