Desolation of Smaug is a rare Sorcery card from The Hobbit (HOB), collector number 226. Current market price: $1.49 (foil $2.46), TCGplayer market prices via Scryfall.
Desolation of Smaug deals 3 damage to each non-Dragon creature. Add four mana in any combination of colors. Spend this mana only to cast Dragon spells.