Black Widow, Daring Operative is a mythic Legendary Creature — Human Spy Hero card from Marvel Super Heroes Commander (MSC), collector number 831. Current market price: $2.96 (foil $5.73), TCGplayer market prices via Scryfall.
Menace (This creature can't be blocked except by two or more creatures.) When Black Widow enters, mill three cards. (Put the top three cards of your library into your graveyard.) Whenever Black Widow deals combat damage to a player, each opponent loses life equal to the number of creature cards in your graveyard.