The Storm Hag's Tattoo

Alter: As an action, you can speak the tattoo’s command word and cause tendrils of electricity to surge through your body for the next 10 minutes. You can end this effect early by using a bonus action to dismiss it.
For the duration, you are resistant to lightning damage. Additionally, whenever a creature comes within 5 feet of you, electricity surges from your body into theirs and the creature must make a DC 15 Constitution saving throw. On a failed save, a creature takes 2d10 lightning damage.
Once used, the tattoo can’t be used again until the next dawn

Attunement: Yes
Materials/cost: 360gp
Placement: Torso
Rarity: Rare
Produced by a special needle, this magic tattoo represents a fearsome creature capable of calling down thunder and lightning.

A (princess) once made a deal with a sea hag in order for her ship and subjects to safely pass through the hag’s stormy waters. Once the ship reached its destination, the (princess) vanished from sight, whisked away to the hag’s lair. There, she would be put to work as the hag’s housekeeper. She did this work without complaint, knowing that her subjects were alive because of her sacrifice. After ten years, the hag set the (princess) free, an unlikely friendship having formed between them. The hag let a bit of her magic flow into the (princess) before she left, manifesting as a mark on her chest. The (princess) did not return to her kingdom, from which no one had come to her aid. Instead, she traveled around the world, helping out wherever and however she could. She eventually settled down with a talented tattoo artist in the far north.