Mawling Maul Warhammer (uncommon)

Burning with ravenous hunger and unquenchable hanger, this mimic-infused weapon struggles relentlessly against the sturdy iron chains that bind it. Loosening the chains stimulates the weapon's digestive juices which, if not quenched, can have caustic consequences for its wielder.

Mimic Unleashed: As a bonus action while holding the hammer, you can loosen the chains restraining the mimic, leaving it free to mercilessly maul your foes. While the chains are loose, the hammer bites targets that it hits, dealing an extra 1d4 piercing damage. If you end your turn holding the hammer while the chains are loose, and you didn't hit a creature with an attack using the hammer that turn, the hammer's excess digestive juices pour down the handle and you take 1d4 acid damage. The chains tighten on their own if the hammer isn't held for 1 minute or if you use a bonus action to tighten the chains while holding the weapon.

Versatile: This weapon can be used with one or two hands. A damage value in parentheses appears with the property—the damage when the weapon is used with two hands to make a melee attack.

Proficiency: martial, warhammer Source: Heliana's Guide to Monster Hunting - Part One p. 451, Player's Handbook (2014) p. 149