Voltage Pulse

Static energy crackles around your body and remains for the duration of the spell unless dismissed as a bonus action or you're incapacitated. At the start of your turns, the energy pulses out 15ft. Every creature within that range must make a Dexterity saving throw or take 3d8 lightning damage on a failed save or half as much on a successful save. Additionally, any creature to hit you with a melee attack within 10ft must make that saving throw again or take the same amount of damage. 

At Higher Levels. When you cast this spell using a higher spell slot of 6th or higher, the damage increases by 1d8 for each slot level above 5th.