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

Unusual Nature. The golem doesn’t require air, food, drink, or sleep.

Multiattack. The golem makes one arc claw attack and one slam attack.

Arc Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 7) slashing damage plus 9 (2d8) lightning damage.. If the target is a Medium or smaller creature, it is grabbed by the claw and grappled.  If a creature is grappled by the arc, the golem can’t attack any other creature with it. Any creature grappled by the claw can free itself at the start of its turn with a successful DC 15 Strength (Athletics) check or is automatically freed if the Abominable Construct takes 30 damage in one turn.

Slam. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 7) bludgeoning damage

Enhanced Shoulder Mounted Pyroconverger (Recharge 3-4). The golem emits a 15-foot cone of petrifying gas from its mouth. Each creature in that area must succeed on a DC 15 Dexterity saving throw or take 21 (6d6) fire damage and is immolated for the next minute. The immolated target sheds bright light in a 30-foot radius and dim light for an additional 30 feet. At the end of each of its turns, the target repeats the saving throw. It takes 3d6 fire damage on a failed save, and the spell ends on a successful one. These flames can only be put out by total submersion in water for a creatures turn or if they use an action to extinguish the flames.