Castigation of Keranos

You point your finger, and the creature that damaged you is momentarily surrounded by arcing sparks of lightning. The target creature and all surrounding creatures in a 5ft radius must make a Dexterity saving throw. All creatures take 1d12 lightning 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 1d12 for each slot level above 1st.