Worldbreaker (Patreon)

Weapon (maul), legendary (requires attunement by a creature with Strength score of 17 or higher)

This titanic hammer resembles a darkened globe of impenetrable black iron. When you hit with an attack made with this magic hammer, it deals 2d12 bludgeoning damage, instead of 2d6. This weapon deals double damage to objects and structures.

In addition, you can use an action to cast the earthquake spell from the hammer (save DC 17), slamming the weapon into the ground as part of the action to cast it. You and up to ten other creatures of your choice that you can see automatically succeed on the saving throw against being knocked prone by the spell. This version of the spell extends from you in a 100-foot radius and doesn't require concentration, but ends at the end of your next turn. Once this property of the hammer has been used, it can't be used again until a number of days have passed equal to half the number of fissures created by the spell (minimum of 1 day).

There are enemies that simply must be defeated, no matter the cost, whose downfall is paramount to all else. Against such threats, collateral damage is not only acceptable, but expected.