Cannon

Siege Monster.  The cannon deals double damage to objects and structures.

Crew. The cannon starts combat with a crew of six, this crew is to represented by humanoid creatures (default to using the Bandit stat block). When a crew member is lost, all actions for the cannon gain the recharge trait at 2. For each additional crew member lost the recharge goes up by one. If all crew members are killed, the cannon is destroyed. The cannon may take more than six crew, up to nine, but this confers no benefit.

Reliability. The cannon, when damaged will start to lose efficacy, if the cannon has taken half or more of its starting hit points in damage, it has disadvantage on all attack rolls, and all creatures targeted by a cannon's attack gain advantage on saving throws against its attacks. If the cannon has lost three quarters of its starting hit points, each attack has a twenty five percent change of causing the cannon to explode. An exploded cannon detaches all crew; any creatures in a 5 ft. radius must make a DC 12 Dexterity saving throw taking 18 (4d8) fire damage on a failed save, half on a successful save; and the cannon is destroyed.

Nonliving. The cannon does receive any benefit from healing from spells or abilities. Instead someone can spend eight or more hours, and make a DC 15 Intelligence (Smith's Tools) tool check to repair all damage to the cannon.

Solid Shot. Ranged Weapon Attack: +6 to hit, range 900/2,700 ft., one target. Hit: 55 (10d10) bludgeoning damage. Creatures struck by this attack must make a DC 15 Strength saving throw or be knocked prone.

Hot Shot. Ranged Weapon Attack: +6 to hit, range 800/2,400 ft., one target. Hit: 33 (6d10) bludgeoning plus 11 (2d10) fire damage. Creatures within 5 ft. of the target must make a DC 15 dexterity throw, or take 18 (4d8) fire damage.

Grape Shot. The cannon fires a burst of canister shot, spraying deadly lead balls out in a 140 ft. cone. Creatures caught within the cone must make a DC 15 dexterity saving throw, taking 22 (4d10) piercing damage on a failed save or half as much on a successful one, swarms take double damage from this attack. 

Take Crew. If any willing humanoid creatures are within 5 ft. of the cannon, they can be taken into the crew, such a creature cannot take actions, or bonus actions and uses the cannon's initiative, saving throws, armor class, and hit points. Creatures that are part of the crew cannot be targeted by spells, attacks, or abilities unless such effects target an area of effect. 

Detach Crew. The cannon can detach any number of crew to be free to act independently, if all crew are detached, the cannon cannot take actions and is considered destroyed if no crew rejoin within three rounds. 

Sacrifice Crew. The cannon's crew can sacrifice themselves to prevent damage to the cannon, if this occurs, up to two crew members take damage instead of the cannon.