Black Lightning Cloak

You are immune to lightning damage. You have the Lightning Absorption trait, and every time you take lightning damage from any source, you heal for half the damage the attack would have inflicted. 

As a bonus action, and for the duration of the spell, you can infuse you melee weapon attacks with Black Lightning. The weapons do an addition d8 of lightning and d4 Necrotic damage.

If you take 4d8 total damage to yourself, you may end the spell early by rejecting the lightning cloak off your body. When you do so, all creatures within a 30ft radius must make a DEXTERITY save (DC 16) or take 4d8 lightning damage - half as much on a successful save - plus any damage done with your melee weapon.