False Truth

Put 2 cards from you hand onto the battlefield
face down. An opponent chooses one of those
cards, reveal that card. Your opponent may have
you return bother cards to your hand or your
opponent may have you discard the revealed
card, if you do you may cast the other card
without paying its mana cost.
There are two rules for success in life. One: never
reveal everything you know. ~ The Riddler