Green Sun's Twilight is a rare Sorcery card from Phyrexia: All Will Be One Promos (PONE), collector number 169p. Current market price: $0.31 (foil $0.57), TCGplayer market prices via Scryfall.
Reveal the top X plus one cards of your library. Choose a creature card and/or a land card from among them. Put those cards into your hand and the rest on the bottom of your library in a random order. If X is 5 or more, instead put the chosen cards onto the battlefield or into your hand and the rest on the bottom of your library in a random order.