Blue Dragons' Rest Stone 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.

Wall of Defense. The Golem's defenses increase when within 5 ft. of another Dragon's Rest Stone Golem. When within 5 ft., both Golems gain +2 to AC and regenerate 1d8 HP if they start their turn within 5 ft. of another Dragon's Rest Stone Golem. 

Activated. These constructs go into sentry mode (activate) when any movement is detected (passive tremor perception of 20) within 60 feet. 

Multiattack. The golem makes two slam attacks.

Slam. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 10 (1d8 + 5) bludgeoning damage.

Slow (Recharge 5–6). The golem targets one or more creatures it can see within 10 feet of it. Each target must make a DC 17 Wisdom saving throw against this magic. On a failed save, a target can't use reactions, its speed is halved, and it can't make more than one attack on its turn. In addition, the target can take either an action or a bonus action on its turn, not both. These effects last for 1 minute. A target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.