Flowstone Flood is a uncommon Sorcery card from World Championship Decks 1999 (WC99), collector number mlp83sb. Current market price: $0.25, TCGplayer market prices via Scryfall.
Buyback—Pay 3 life, Discard a card at random. (You may pay 3 life and discard a card at random in addition to any other costs as you cast this spell. If you do, put this card into your hand as it resolves.) Destroy target land.