Plumb the Forbidden is a rare Instant card from Secret Lair Drop (SLD), collector number 7114. Current market price: $4.06 (foil $4.89), 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.