Fire Absorption. Any Fire damage dealt to the MIC is added instead of subtracted. 

Freeze. If the MIC takes Cold damage, it freezes so that it becomes Paralized of 1 minute until the effect ends or until it takes Fire damage, which ends the effect early.

Heated Body. A creature that touches the MIC or hits it with a melee attack while within 5 ft. of it takes 13 (3d6) Fire damage. This damage is doubled while Heat Metal is cast on it.

Heated Weapons. Any metal melee weapon the MIC wields deals an extra 17 (4d6) Fire damage on a hit (included in the attack). This damage is doubled while Heat Metal is cast on it.

Innate Spellcasting. (3/day) The MIC can innately cast Heat Metal on itself as a bonus action, without any components. 

Mechanical Immortalness. The MIC doesn't need to breathe, eat or sleep to live. It must only drink 1 gallon of oil to maintain itself each day.

Power Down. Instead of sleeping, the MIC powers down for a given period of time. The MIC powers down for 30 minutes for a short rest or 4 hours for a long rest. The rules for resting are otherwise the same. Either way, the MIC isn't deprived of sight while resting.

Quad-armed. The has two pairs of arms. 

Multiattack. The MIC makes three attacks. One with it's Greataxe and two with it's Spiked Shield. It can replace the Spiked Shield attacks with a Greatclub attack, a Slam attack or, if it's available, it's Fire Breath.  

Greataxe. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 32  (4d12 + 5) Slashing damage plus 17 (4d6) Fire damage. 

Greatclub. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 20 (5d8 + 5) Bludgeoning damage plus 17 (4d6) Fire damage and the target must succeed a DC 18 STR saving throw or be launched up to 20 ft. and fall Prone. 

Slam. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 18 (6d4 + 5) Bludgeoning damage plus 30 (7d6) Fire damage. 

Spiked Shield. Melee Weapon Attack: +11 to hit, reach 5 ft., 1 target. Hit: 19 (7d4 + #) Piercing damage plus 17 (4d6) Fire damage.

Fire Breath (Recharge 5-6). The MIC exhales fire in a 60 ft. cone. Each creature in that area must make a DC 18 Dexterity saving throw, taking 56 (16d6) Fire damage on a failed save, or half as much damage on a successful one.