Flashback is a rare Instant card from Secrets of Strixhaven (SOS), collector number 333. Current market price: $5.92 (foil $9.06), TCGplayer market prices via Scryfall.
Target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost. (You may cast that card from your graveyard for its flashback cost. Then exile it.)