Memory Deluge is a rare Instant card from Innistrad: Double Feature (DBL), collector number 62. Current market price: $0.55 (foil $2.06), TCGplayer market prices via Scryfall.
Look at the top X cards of your library, where X is the amount of mana spent to cast this spell. Put two of them into your hand and the rest on the bottom of your library in a random order. Flashback {5}{U}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)