Gauss Ring

Ring, legendary (requires attunement)

This ring of braided copper and crystal wire is typically unadorned with any stones. You gain resistance to lightning damage, with lightning damage prevented by this resistance absorbed into the gauss ring, up to a maximum of 60 points per day. Each round as a reaction, you can charge your melee attacks with stored lightning damage. While your melee weapon attacks are charged in this way, you gain advantage on melee weapon attack rolls against creatures made of metal or that are wearing metal armor. If a charged melee attack hits, it deals an extra 1d6 lightning damage to the target, dissipating that charge. This lightning damage is dissipated without effect if you do not hit a creature with a melee attack before the beginning of your next turn. If you do not use a reaction in this way while you have lightning stored in your gauss ring, you can discharge 1d6 lightning damage as a reaction when you are struck with a natural weapon, unarmed strike, or melee weapon attack with a metal weapon. If a creature attempts to grapple you, you can discharge 2d6 lightning damage as a reaction; the grappler takes this damage and disadvantage on ability checks made to grapple you until the end of its next turn. Unused lightning stored in a gauss ring fades 24 hours after being absorbed. Lightning discharged by a gauss ring cannot be absorbed by it.

Epic Attunement. You are instead immune to lightning damage and the amount of electricity you can store is 10 times your level, with a minimum of 60. Furthermore, if you score a critical hit on a creature, with a melee weapon attack you charged with lightning, you can discharge an additional 1d10 lightning damage into the attack. If you discharge lightning into an creature as a reaction when that creature scores a critical hit against you in melee, you can discharge 1d10 lightning damage against that creature.

Finally, you gain the ability to discharge lightning in the form of a bolt of lightning that fills a 60-foot line. The Dexterity DC to halve the damage equals 8 + your Intelligence modifier + your proficiency bonus. This bolt of lightning discharges 6d6 lightning damage.

You can only use this bolt of lightning once before needing to complete a long rest.