Mage's Enhancements. The giant has advantage on all intelligence, wisdom, and charisma saving throws against magic.
Reduce. The golem can reduce its size to huge at will but suffers disadvantage on cannon attacks and a -4 penalty on all attack and damage rolls. The golem slowly returns to gargantuan size after 1 hour. If the enlarge/reduce spell is used to reduce the golem's size, this ability automatically activates. A successful DC 15 casting of dispel magic also activates this ability.
Siege Cannons. The golem deals double damage to and has advantage to hit all structures that it attacks with its cannons. On a critical hit, if the structure is below 100 hp do not roll damage, instead instantly destroy the structure. There is one cannon on each of the golem's arms, each cannon has an AC of 18, 70 hit points, and immunity to poison and psychic damage. If a cannon is destroyed, the golem only recharges its canon attack on a roll of 6.
Giant Toppler. The canon golem has advantage on all attack rolls made against huge or gargantuan creatures.
Multiattack. The golem makes two crush attacks.
Crush. Melee Attack: +12 to hit, reach 10 ft., one target. Hit: 22 (3d8 + 9) bludgeoning damage.
Cannons (Recharge 4-6). Ranged Weapon Attack: +9 to hit, range 600/2400 ft., one target. Hit: 44 (8d10) bludgeoning damage. On a critical hit, the target must succeed three saving throws; a DC 18 Strength saving throw or be knocked prone, a DC 17 Dexterity saving throw or be pushed back 2d6 x 5 ft., and a DC 16 Constitution saving throw or suffer one level of exhaustion. Also on a critical hit, reroll all 1s on damage dice until they are no longer 1s.
Repair Drones. Whenever the golem loses a canon, a repair drone pops out of the golem's shoulder. The golem has one drone for each canon. The drones have AC 15, 20 hit points, and they attempt to repair a canon on the end of the golem's turn. A drone can repair a canon in 3 rounds unless it is destroyed. If a drone is destroyed, the second will attempt to continue the other's work.
Magical Resistance. When the canon golem fails a saving throw against a spell that would charm, frighten, or distract it; the golem can add an additional 3d6 to the roll. This ability can be used once per day and recharges at dawn.
Description
This gargantuan construct is a masterwork creation of ancient Dwarven siege mages. It resembles an iron golem in appearance however its arms are instead canons.
Castle Toppler. The Dwarven mages created these golems with the intent to use them to defend their grand keeps against incoming siege equipment. Many Dwarven generals were impressed with how effectively these golems dealt with enemy equipment and these golems were eventually used offensively against castle walls.
Magical Resilliance. Some powerful mages figured out how to turn some early canon golems against Dwarven citadels. After they were used in this manner, the dwarven enchanters started using a magical metal in the creation of these golems. This metal grants the golems resistance to many magical effects.
Giant Slayers. In addition to castles, it was found that a canon golem could make quick work of many giant creatures. The fall of the giants' empire is partially contributed to these canon golems. In fact, many canon golems were created with the intent of being used against giants. These canon golems are distinct in that they are covered in Dwarven scripts and runes. Due to the nature of their creation, these canon golems will prioritize attacking giants over any other creature, This effort to destroy giants will go so far to cause the golem to be indifferent to any other creature.