Multiattack

The golem makes four Spear Arm attacks. It can replace one Spear Arm attack with a Shield Bash attack.

Shield Bash

_Melee Weapon Attack:_ +12 to hit, reach 5 ft., one target. _Hit:_ 29 (4d10+7) bludgeoning damage, and the target must succeed on a DC 18 STR save or be knocked prone.

Spear Arm

_Melee Weapon Attack:_ +12 to hit, reach 10 ft., one target. _Hit:_ 25 (4d8+7) piercing damage.

Expel Poisonous Gas (Recharge 5-6)

The golem vents poisonous gas from small holes across its body. Each creature within 15 feet of the golem must make a DC 18 CON save, taking 54 (12d8) poison damage on a failed save, or half as much damage on a successful one.