Hammer of Thunderbolts
Very rare magic weapon (maul)
Property: If you are Medium or larger and have an 18 Strength or higher, you gain a +1 bonus to the attack rolls and the damage rolls you make with this weapon.
Property: The weapon’s bonus to attack rolls and damage rolls increases to +2, and you deal 3d6 extra damage when you hit a dragon or giant with this weapon. In addition, the weapon gains the thrown property with a range of 50/120 feet. If you hit a creature with an attack made by throwing this weapon, it issues a deafening thunderclap. Each creature within 30 feet of the target must make a DC 15 Constitution saving throw. A creature takes 3d6 thunder damage on a failed save, and half as much damage on a successful one. A creature that fails the save is also deafened for 1 hour.
This large, extra‐heavy maul sports a storm motif on its sledge and along the metal haft. The weapon is quite heavy, weighing about 50 pounds. When first held, the maul sparks with tiny bolts of lightning. Long ago, storm giants used these weapons to hunt the mountain heights for dragons and rival giants. Nearly all record of these thunderous mauls has been lost. If any remain, they are likely within the hoard of a dragon or a giant who was the match of its ancient hunter.