Multiattack

Two Chain attacks.

Chain

Melee Weapon Attack: +7 to hit, 15 ft., one target, 18 (4d6+4) slashing damage and target contracts infernal tetanus disease (see above; DC 16 Con not diseased). Target is grappled (escape DC 14) if it is a Large or smaller creature and golem doesn't have another creature grappled.

Imprison

Creates prison of chains around an up to Med creature grappled by it. Imprisoned: restrained and takes 14 (4d6) piercing damage at start of each of its turns. Imprisoned creature or creature within 5 ft. of golem can use action to free imprisoned creature. Doing so requires DC 16 Str check and creature attempting takes 7 (2d6) piercing damage.