Tzeentch's Firestorm is a direct damage spell. Place the small round template anywhere within 30" – it then scatters D6". All models hit by the template suffer a Strength D6 hit with the Warpflame special rule (roll once for the Strength and use that value for all hits). The Wizard can choose to create a larger firestorm, using the large round template rather than the small one. If he does so, the casting value is increased to 16+ and the template scatters 2D6" rather than D6".