Egberticus's Eelskin Evasion

Your skin begins to rapidly discharge electrical energy in a 5 foot Emanation for the duration. When you initially cast the spell and at the start of each of your turns for the duration of the spell, each creature within the Emanation must make a Constitution saving throw. The creature grappling you has disadvantage on these saves. On a failed save, the creature takes 1d6 Lightning damage.  The spell ends early if the Grappled condition ever ends on you.

Cantrip Upgrade. The damage increases by 1d6 when you reach levels 5 (2d6), 11 (3d6), and 17 (4d6).