Clockwork Dragon Guardian

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

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

Metallic Body. The body of the dragon is created out of metal and thus is immune to every illness and poison. Additionally, the dragon doesn't require food, water or air to survive.

Screaming Aura. The constant metallic scratching when the dragon moves, leads to horrible mental struggling for those who come too close. Every creature in a 30-foot radius that can hear the dragon has to succeed on a DC 18 Wisdom saving throw or else takes 12 (2d10) psychic damage.

If you succeed on the saving throw, you become immune against the aura of this dragon for 24 hours.

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

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 26 (3d10 + 8) piercing damage.

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 23 (3d8 + 8) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 29 (3d12 + 8) piercing damage.

Frightful Presence. Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 17 Wisdom saving throw or become frightened for 1 minute. 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 dragon's Frightful Presence for the next 24 hours.

Steam Odem (Recharge 5–6). The dragon exhales hot and rusty looking, poisonous gas in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 48 (12d6) fire damage and 16 (4d6) poison damage, or half as much damage on a successful one.

The dragon can take 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 dragon regains spent legendary actions at the start of its turn.

Hot Gas (costs 2 actions). The dragon surrounds itself with a hot steam, which streams out the heavy construct's body. Every creature in a 30 ft. radius has to make a DC 17 Constitution saving throw or else take 20 (4d8) fire damage and half the damage on a successful one. Creatures within this radius have to make this saving throw every round.

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 10 feet of the dragon must succeed on a DC 20 Dexterity saving throw or take 16 (2d6 + 8) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.