Creature - Sphinx 3/4, 2WWW (5) {T}: Target player names a card, then reveals the top card of his or her library. If that card is the named card, that player puts it into his or her hand. If it isn't, the player puts it into his or her graveyard.1
Illus. Sandra Everingham
The revealing of a card for the Sphinx does not count as "drawing" a card for purposes of Underworld Dreams or any other effect which looks at cards drawn. [Aahz 1994/06/22]
You will not lose the game if there are no cards in your library when the Sphinx is used on you. It simply does nothing. [Aahz 1994/06/22]
Extended tournaments (see Rule 803) have banned this card since 1999/10/01.