Sulfurous Blast is a uncommon Instant card from Conspiracy: Take the Crown (CN2), collector number 170. Current market price: $0.07 (foil $0.32), TCGplayer market prices via Scryfall.
Sulfurous Blast deals 2 damage to each creature and each player. If you cast this spell during your main phase, Sulfurous Blast deals 3 damage to each creature and each player instead.