Construct Dragon

Siege Monster. The dragon deals double damage to objects and structures 

Unusual Nature. The dragon doesn't require air, food, drink, or sleep, and it gains no benefits from finishing a short or long rest, cannot heal from any source of healing yet can be repaired outside of combat to max health every dawn to max health until then it cannot be repaired.

Blacksmith's Tool. There is a hiddin chamber within the dragons chest that can be opened to reveal blacksmith's tools used to repair the creature.

Multiattack. The dragon can use its Malevolent Presence. It then makes three attacks: two with its claws and one with its tail.

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) bludgeoning damage.

Malevolent Presence. Any creature with an intelligence of 4 or more that is within 30 feet of the dragon must succeed on a DC 14 Wisdom saving throw or be feared by it for 1 minute, the person soul bound to it is immune to it's fear effect. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragons malevolent presence for the next 24 hours.

Necrotic Breath (Recharge 5–6). The dragon exhales a ray of necrotic energy in a 120-foot line. Each creature in that line must make a DC 16 Dexterity saving throw, taking 21 (6d6) necrotic damage on a failed save, or half as much damage on a successful one.