Decay Flames

You hold your hands up, as thin sheet of black flames shoots forth. Each creature in a 15-foot cone must make a Dexterity saving throw. A creature takes 1d6 fire damage and 1d6 necrotic damage on a failed save, or half as much damage on a successful one.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.