Arm of the Mounts

Dormant State: The wielder's Strength and Constitution scores become 19. When an attack roll hits with a Two Handed or Versatile weapon while attuned to the arm, a loud boom echoes 300 feet, as if a titan had stepped on the earth, and the target of the attack must succeed on a DC 17 Constitution saving throw or become deafened until the end of their next turn. If the attuned creature has the Rage feature, rage damage is doubled.

Waking State: The wielder's Strength and Constitution scores become 21. While attuned to the arm, the wearer can use their bonus action to slam it into their chest, creating a loud boom echoing 300 feet. Upon using this bonus action, they grow one size larger, and gain the Siege effect, dealing double damage to structures and objects. They also gain resistance to fire, cold and lightning damage while in this size. This enlarged state lasts for 10 minutes, or until a bonus action is used to shrink back down. They can use this feature once per Long Rest. The wearer also gains all the effects in the Dormant State.

Awakened State: The wielder's Strength and Constitution scores become 23. Upon using the bonus action to slam the arm into the wielder's chest, they instead grow 2 sizes larger. In addition, while in this size, the attuned creature gains resistance to all types of damage except poison and psychic, as the skin turns to a stone-like texture. The wielder also gets a critical hit on a roll of 19 or 20 on the d20, even out of the enlarged state. The wearer also gains all the effects in the Waking State.

Notes: Set: Strength Score, Set: Constitution Score, by a Barbarian, Fighter, Paladin or Ranger, Combat