Quake Hammer

The Quake Hammer is an intimidating weapon, with the head and hilt enchanted with ancient dwarven runes. Using an action, the Quake Hammer can be powered up to produce a bright light and then be slammed into the ground to cause a powerful shockwave. Any creature within 10ft of the strike must succeed a Dex Saving Throw of 15 or be knocked prone, taking 1d8 + STR bludgeoning damage or half that on a success. 
This puts a tremendous strain on the body of the hammer's wielder, and it can only be done safely a number of times equal to the creature’s Constitution Modifier per Long Rest. When done any more times, the wielder takes 1d6 + STR Bludgeoning Damage with each attempt.

Item type

Weapon, Melee