Rubber Golem

Bludgeoning Backlash. Whenever the golem is subjected to bludgeoning damage from a melee attack, it may use its reaction to shove the source of the bludgeoning damage. Any creature subject to this backlash must make an Atheletics or Acrobatics check vs DC 16 or be pushed back 5 feet and knocked prone

'Berserk. 'Whenever the golem starts its turn with 50 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 attacks are magical.

ACTIONS
Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 16 (2d10+5) bludgeoning damage.

Stretch. The golem makes a slam, grapple, or shove with 20 foot reach. A creature grappled in ths way gets pulled to a space adjacent to the golem.