Black Lightning Blossom

A spinning blue ball of flame, crackling with black lightning, flashes from your pointing finger to a point you choose within range and then blossoms into a explosion of lightning connecting around allies and to enemies in range. Each creature in a 20-foot-radius sphere centered on that point must make a Dexterity saving throw. A target takes 3d6 lightning damage on a failed save, or half as much damage on a successful one.

The damaging elements only burn what the caster wants to burn, allies to the caster are immune to the damage caused by the spell, as its effects go around them.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 2d8 fire damage for each slot level above cantrip.