Berserk. Whenever the golem starts its turn with 60 hit points or fewer, roll a d6. On a 6, the golem goes berserk. On each of its turns while berserk, the golem attacks the nearest creature it can see. If no creature is near enough to move to and attack, the golem attacks an object, with preference for an object smaller than itself. Once the golem goes berserk, it continues to do so until it is destroyed or regains all its hit points.

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 other magical effects.

Magic Weapons. The golem's weapon attacks are magical.

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d10 + 5) bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Dexterity saving throw. On a failed save the target is considered grappled.

Bind. If the Yarn Golem has a target grappled at the start of its turn it may use a bonus action to bind the target. Target makes a DC 15 Dexterity saving throw. On a failed save the target is considered incapacitated. It may use an action on its turn to succeed a DC 15 Strength check to break the binding.