Clockwork Reliquary

Adamantine Shell. The reliquary's casing, except for its glass container, is made of adamantine metal, which negates all critical hits that land on it.

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

Magic Resistance. The reliquary has advantage on saving throws against spells and other magical effects.

Multiattack. The reliquary makes two attacks with its claws and three attacks with its darts.

Claws. Melee Attack Roll: +17, reach 10 ft. Hit: 43 (6d10 + 10) Slashing damage.

Darts. Ranged Attack Roll: +9, range 30 ft. Hit: 23 (6d6 + 2) Piercing damage.

Sphere Discharge (Recharge 5-6). All creatures within a 30 ft. radius must succeed on a DC 18 Constitution saving throws or take 21 (6d6) Force damage and be stunned for 1 turn on a failed save, or half as much damage on a successful one.

Protection. Trigger: An attack roll hits the reliquary while other constructs (minimum of one) is within 5 feet of it. Response: The reliquary shunts half the damage to nearby constructs, splitting the damage equally among them.

The reliquary can make 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. The reliquary regains spent legendary actions at the start of its turn.

Claws. The reliquary makes one claws attack.

Skittering. The reliquary moves up to its full movement speed without provoking opportunity attacks.

Repairs (Costs 2 Actions). The reliquary destroys a nearby construct and absorbs its remaining hit points, using its parts to repair itself instantly and magically.