Flashfire

You cause flames to spring up in the area of effect. These flames deal (min(5,CASTERLEVEL/3))d6 points of fire damage to each creature that enters a burning area or begins its turn in the area; these creatures also catch on fire. A creature that succeeds at a Reflex save negates the damage and avoids catching on fire. The area and all adjacent 5-foot squares are smoky, providing concealment within. You can concentrate as a standard action to ignite one 5-foot square adjacent to a currently burning square. Heavy precipitation (including sleet storm) ends the spell. Strong and severe winds spread each square of flashfire downwind by one square each round, but windstorm-force or stronger winds extinguish the fires.