Brass Monkey

Cold Aura. At the end of each of the Brass Monkey's turns, each creature in a 5-foot Emanation originating from the Brass Monkey takes 13 (3d8) Cold damage.

Poor Lubricant. The Brass Monkey cannot take reactions.

Multiattack. The Brass Monkey makes two Cannon attacks or one Cannon Ball attack.

Cannon. Ranged Attack Roll: +6, range 600/2,400 ft. Hit: 44 (8d10) Bludgeoning damage.

Cannon Ball (Recharge 6). A The Brass Monkey uses a targeting laser to select a point it can see within 100 feet. At an initiative count of the Brass Monkey's initiative +5 the Brass Monkey throws itself up into the air and down onto that point. If the point is on land, the Brass Monkey's movement speed is then reduced to 0 for 2 rounds. Dexterity Saving Throw: DC 17, each creature in a 5-foot-radius Sphere centered on that point. Failure: 110 (20d10) Bludgeoning damage. On failure resulting from a natural 1, the target is brought instantly to 0 hit points. If the target is a Large or smaller creature, it has the Prone condition. Success: Half damage only. 

Maintenance (1/day). The Brass Monkey curls into a ball and gains +5 to its AC. While in this form, it automatically fails dexterity saving throws, attacks have advantage on it, takes no actions or movement, and regains 1d20+5 hit points at the start of each of its turns. Each creature that rolls a melee attack against the Brass Monkey takes 1d10 lightning damage. It stays in this form until fully healed or until 25 damage or more is dealt to it. If broken out the Brass Monkey is stunned until the end of its next turn.

Shriek (Recharge 6). All creatures within hearing distance of the Brass Monkey must succeed on a DC 17 Constitution saving throw or take 3d10 thunder damage.