Shutdown. If targeted by dispel magic, the horror must succeed on a Constitution saving throw against the caster's spell save DC or fall unconscious for 1 minute or until it takes any damage.
Unusual Nature. The horror doesn't require air, food, drink, or sleep.
Multiattack. The horror makes one Bite attack and two Rotating Saw attacks, or it makes two Lightning Jolt attacks.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit:6 (1d8 + 2) piercing damage.
Rotating Saw. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit:4 (1d4 + 2) slashing damage.
Lightning Jolt. Ranged Spell Attack: +4 to hit, range 120 ft., one target. Hit:7 (1d10 + 2) lightning damage.
Spelljamming Helm Interface. The horror attaches to a spelljamming helm it can see within 5 feet of itself and attunes to the helm instantly. If another creature is already attuned to the helm, that creature's attunement to the helm ends when the horror's attunement begins. The horror can operate the helm even though it isn't a spellcaster. The horror can detach from the helm as a bonus action, which ends its attunement to the helm.
Clockwork horrors are ruthless insectile automatons—eldritch machines encased in adamantine or some other precious metal. They roam Wildspace in commandeered spelljamming ships, gathering the precious metals and crystals they need to build more of their kind. Clockwork horrors have no goal beyond replication and will stop at nothing to create new clockwork horrors. The time it takes for a clockwork horror to build another of its kind, assuming it has the requisite materials, is approximately…