Mordenkainen's Lost Notebook

Incendiary Surge

6-level Evocation

No sooner has a blast of white-hot fire burst forth from your hands than you feel it building within you again. Each creature in a 60-foot cone must make a Dexterity saving throw. A creature takes 8d6 fire damage on a failed save, or half as much damage on a successful one. A creature reduced to 0 hit points by this spell is instantly slain, reduced to ash. In addition, if you cast incendiary surge again before the end of your next turn, the second casting deals 8d8 fire damage.
At higher levels: At Higher Levels. When you cast this spell using a spell slot of 7th level or higher, the damage increases by 1d6 for each slot level above 6th.