Circle of Lightning

Channeling your arcane power you map and a lightning sigil to a surface within 30 ft of you. This sigil has a 10-foot-radius. Anybody within the spell's radius can change the damage type of any spell they cast to lighting.

When you cast this spell using a spell slot of 2nd level or higher, lighting spells cast within the radius deal an additional 1d4 damage for each slot level above 1st.