Volcanic Torrent is a uncommon Sorcery card from Outlaws of Thunder Junction Commander (OTC), collector number 184. Current market price: $0.26, TCGplayer market prices via Scryfall.
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.) Volcanic Torrent deals X damage to each creature and planeswalker your opponents control, where X is the number of spells you've cast this turn.