Web Golem

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.

Spider Climb. The golem can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Webbed Insides. When the golem drops to half of its maximum hit points or lower, the layer of silk covering it comes loose, exposing its flammable insides. The golem's AC decreases by 2 and it gains vulnerability to fire damage. Its protective outer layer regenerates after it takes a short or long rest. 

Web Walker. The spider ignores movement restrictions caused by webbing.

Multiattack. The golem makes two slam attacks, one of which it can replace with either its bite or its web spit, so long as either or both of them are available.

Slam. Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Bite (Recharge 5-6). Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) piercing damage, and the target is injected with poison. The target must succeed on a DC 16 Constitution saving throw or have its Strength score reduced by 1d4. The target dies if this reduces its Strength to 0. Otherwise, the reduction lasts until the target finishes a short or long rest. 

Web Spit (3 times per long rest). The golem spits out a large quantity of webs. This mimics the effects of the Web spell (Save DC 16), but does not require concentration.