Magic Weapon (Maul), Artifact (Requires Attunement)
This magical weapon appears as a two-handed maul of tarnished bronze, the head of which is shaped like a giant squid grappling a ship.
This weapon gains an enchantment bonus, equal to half your proficiency bonus rounded down, to attack and damage rolls.
Scuttle - 1/day
As an action you cause a wave of thunderous force to sweep out from the hammer. Each creature in a 15-foot cube originating from you must make a Constitution saving throw. On a failed save, a creature takes 2d8 thunder damage and is pushed 10 feet away from you. On a successful save, the creature takes half as much damage and isn’t pushed.
When you use this item, the thunder damage increases by 1d8 for every 2 levels you are above 1st. 3rd level (3d8), 5th level (4d8), 7th level (5d8), 9th level (6d8), 11th level (7d8), 13th level (8d8), 15th level (9d8), 17th level (10d8), and 19th level (11d8)
In addition, unsecured objects that are completely within the area of effect are automatically pushed 10 feet away from you, and unattended non-magical objects in the area take the maximized thunder damage.
Bludgeoning and thunder damage from the hammer is doubled against wooden objects.
If the Krakenhammer is bathed in the fresh blood of a Megladon then the hammer now permanently deals 3d6, and double damage against stone.
Destroying the Hammer
The Krakenhammer must be hung to dry for one month in a smokehouse, alongside dried seaweed harvested from a Kraken's lair. Over this time the Krakenhammer will visibly shrivel, and afterwards it must be kept absolutely dry or the process will need to be started anew. In this state, it can be struck tremendously (DC 20 Strength check) against the top of a mountain, where it will shatter. Once shattered, nothing can repair it.
The Krakenhammer was a unique item originally created for a player in a Pathfinder campaign a long time ago. That campaign was in progress during the release of 5th Edition D&D and the item had to be converted when we switched systems.