Blackflame

You choose a flame that you can see within range and that fits within a 5-foot cube. The flame momentarily changes colour into a deep black, and then lashes out at surrounding creatures. Each creature within a 5-foot radius extending from the flame must make a Dexterity saving throw. A creature takes 1d6 necrotic damage and 2d6 fire 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 necrotic damage increases by 1d6 for each slot level above 1st.