Lightning Absorption. Whenever the golem is subjected to lightning damage, it takes no damage and instead regains a number of hit points equal to the lightning damage dealt.

Immutable Form. The golem is immune to any spell or effect that would alter its form.

Magic Resistance. The golem has advantage on saving throws against spells and magical effects.

Magical Weapons. The golem's weapons are magical.

Oil Spill. The golem covers the ground a 10ft square within 60ft of it with oil and turns it into difficult terrain for 1 minute.

Each creature standing in its area must succeed on a DC 15 Dexterity saving throw or fall prone. A creature that enters the area or ends its turn there must also succeed on a Dexterity saving throw or fall prone.

Multiattack. The golem makes three melee attacks.

Slam. Melee Weapon Attack: +16 to hit, reach 5ft., 1 target. Hit: 23 (3d8 + 10) bludgeoning damage. 

Flail. Melee Weapon Attack: +16 to hit, reach 10ft., 1 target. Hit: 26 (3d10 + 10) bludgeoning damage.

Force Cannon. Ranged Weapon Attack: +10 to hit, range 50 ft., one target. Hit: 22 (4d10) force damage, and the target is knocked prone if it is a creature of size Medium or smaller.

Flamethrower (Recharge 5-6). The golem shoots fire in a 100ft long and 5ft wide line. Each creature in that area must make a DC 20 Dexterity saving throw, taking 45 (10d8) fire damage on a failed save, or half as much damage on a successful one.

Coolant Spray (Recharge 5-6). The golem sprays its coolant in a 30ft cone. Each creature in that area must make a DC 20 Constitution saving throw, taking 45 (10d8) cold damage on a failed save, or half as much damage on a successful one.

Shock-wave (Recharge 6). The golem produces a lightning shock-wave in a 20ft sphere. Each creature in that area must make a DC 20 Constitution saving throw, taking 22 (4d8) lightning damage and is stunned until the start of the golem's next turn on a failed save, or half as much damage and is not stunned on a successful one.

The golem can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The golem regains spent legendary actions at the start of its turn.

Slam or Flail Attack (Costs 1 Actions). The golem makes one slam attack or uses its flail.

Force Cannon (Costs 2 Actions). The golem uses its Force Cannon.

Oil Spill (Costs 3 Actions). The golem creates an oil spill.