Slow-Burn Fireball

3rd-level evocation

Casting Time: 1 action

Range: 150 feet

Components: V, S, M (a small chunk of coal and sulfur)

Duration: Instantaneous

A bright streak flashes from your pointing finger to a point you choose within range, where it slowly ignites the air itself with phlogiston. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw, taking 4d6 fire damage on a failed save, or half as much damage on a successful one. Each creature then takes the same amount of damage at the start of each of its turns for the next two turns. A creature can prevent this extra damage by using an action to put out the flames on itself. The spell ignites flammable objects in the area that aren’t being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d6 for each slot level above 3rd.