Ulfgar's Lightning Punishment

A ionized air leaves a metalic taste in the mouth of any creature in the spell area. All enemies in a 20 feet square take 4d10 lightning damage; enemies in the area lose their reactions and make a Constitution saving throw; on a fail they are stun until the end of their next turn; on a sucess they take half damage. 

Enemies wearing any kind of metal equipment in the spell area have disadvantage on their saving throws against this spell.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d10 for each slot level above 3th.