Forbidden Alchemy is a rare Instant card from Friday Night Magic 2012 (F12), collector number 7. Current market price: — (foil $0.63), TCGplayer market prices via Scryfall.
Look at the top four cards of your library. Put one of them into your hand and the rest into your graveyard. Flashback {6}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)