Blue Dragon Horn Shield

Armor (shield), legendary (requires attunement)

This shield is carved out of the horn of an ancient blue dragon. While holding it, you gain resistance to lightning damage and a +2 bonus to your AC. This bonus is in addition to the shield's normal bonus to AC. While holding the shield, you can use the following properties.

Lightning Weapon. You can use a bonus action to drag a weapon you're wielding across the face of the shield to charge it with electricity. The first time you hit a target with the charged weapon in the next minute, the attack deals an extra 8d12 lightning damage to the target. Once this property of the shield has been used, it can't be used again until the next dawn or until you take lightning damage while holding the shield.

Shield Charge. If you move at least 20 feet in a straight line toward a target, you may immediately make a melee attack against it as a bonus action using the shield. You are proficient with the attack, which uses your Strength modifier for its attack and damage rolls. On a hit, the target takes 2d12 bludgeoning damage and 4d12 lightning damage and must succeed on a Strength saving throw with DC equal to your strength score or be knocked prone.

"Few creatures can harness the power of lightning, even fewer can control it. Our feeble bodies are not among them. So we must use what we can to protect ourselves from those that do."