Black Sun's Twilight is a rare Instant card from Phyrexia: All Will Be One (ONE), collector number 383. Current market price: $0.50 (foil $0.58), TCGplayer market prices via Scryfall.
Up to one target creature gets -X/-X until end of turn. If X is 5 or more, return a creature card with mana value X or less from your graveyard to the battlefield tapped.