Conundrum Sphinx is a rare Creature — Sphinx card from Commander 2011 (CMD), collector number 42. Current market price: $0.30, TCGplayer market prices via Scryfall.
Flying Whenever this creature attacks, each player chooses a card name. Then each player reveals the top card of their library. If the card a player revealed has the name they chose, that player puts it into their hand. If it doesn't, that player puts it on the bottom of their library.