Unrestrained Power

As you thrust your arm forward, voltaic power surges from your core, as lightning is released from your unnaturally bent fingers. When you cast the spell — and as a bonus action on each of your turns thereafter — you can discharge the electrical energy resting in your core, and each creature in a 20-foot cone must make a Constitution saving throw. A creature takes 1d12 lightning damage on a failed save, or half as much damage on a successful one.

The lightning ignites flammable objects in the area that aren't being worn or carried.

At Higher Levels. When you cast this spell using a spell slot of 3rd level or higher, the damage increases by 1d12 for each slot level above 1st.