Moonstone, Harsh Mistress is a uncommon Legendary Creature — Human Doctor Villain card from Marvel Super Heroes (MSH), collector number 107. Current market price: $0.19 (foil $0.32), TCGplayer market prices via Scryfall.
Flying Whenever you discard a card, you may exile that card from your graveyard. If you do, until the end of your next turn, you may play that card.