Plumb the Forbidden is a uncommon Instant card from Strixhaven: School of Mages (STX), collector number 81. Current market price: $0.49 (foil $1.34), TCGplayer market prices via Scryfall.
As an additional cost to cast this spell, you may sacrifice one or more creatures. When you do, copy this spell for each creature sacrificed this way. You draw a card and lose 1 life.