Ancient Automatons Dragon hunter (Vault)

Legendary Resistance (4/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Colossal. The dragon is immune to forced movement, does not provoke opportunity attacks and cannot make opportunity attacks. 

In addition, whenever the dragon makes a weapon attack, regardless of whether the attack hits or misses, each creature within 10 feet of the attack's target other than the target or the dragon itself must succeed on a DC 27 Dexterity saving throw or takes half the attack's damage

Devour. This dragon can devour mass and energy to power it self. Giving it 16 Charges

Vaults Commander.  The Vault has given the dragon an ai that allows it to command Automatons and form strategy through this is based on the Vaults knowledge of making them

 Multi-Cored. This being posses multiple cores a cannot die if it still has 2 or more cores and if all 4 are destroyed it will immediately dies. Attacking a core directly add +3 to its AC

• Core of Wind. With this core active the dragon can manipulate the air and wind in a 500ft area around it and can freely control it. If the core is destroyed it will course an implosion of air within a 1000ft will be pulled towards it. This core can take up 170 damage
• Core of Gravity.  With this core active the dragon can manipulate Gravity in an 500ft area around it and can freely control it. If the core is destroyed it will course gravity within a 1000ft will be unstable. This core can take up 170 damage.
• Core of  Ice.  With this core active the dragon has immunity to cold and fire damage. if this core is destroyed it will course a 1000ft explosion causing  the entire area to be come Icey terrain and will take (12)4d6 Radiant damage per turn. This core can take up 120 damage.
• Core of Rejuvenation. With this core active it can heal 40 health on it main body or 15 health to any core. if this core is destroyed the dragon can no longer heal. this core can take up to 120 damage
• Core of  Sun. with this core active the dragon is considered alive . At the start of the dragon's turn, all creatures within 20 feet of it take 9 (3d6) fire damage and 9 (3d6) Radiant damage .A creature also takes 9 (3d6) Radiant damage if it touches the dragon or hits it with a melee attack while within 20 feet of it. if the core is destroyed the dragon will instantly die and the core will go supernova dealing (30d6) fire damage and (30d6) Radiant damage. This core can take up to 400 damage

   

Vault Possession. The Vault can complete take control over the dragon making it far more competent strategy and in commanding other Vault Automatons

Absolute Movement. The dragon can move across and ANY surfaces without needing to make an ability check. Additionally, Difficult Terrain doesn’t cost it extra movement. This ability doesn't work it Core of Gravity is destroyed .

Tail. Melee Weapon Attack: +19 to hit, reach 35 ft., one target. Hit: 21 (2d10 + 10) bludgeoning damage plus 21 (6d6) fire damage and the target must make a DC 27 Strength saving throw or be knocked prone.

Bite. Melee Weapon Attack: +19 to hit, reach 25 ft., one target. Hit: 23 (2d12 + 10) piercing damage plus 21 (6d6) fire damage and the dragon can grapple the target as part of that attack.

Claw. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 21 (2d10 + 10) slashing damage plus 21 (6d6) fire damage. If the target is a creature, it must succeed on a DC 27 strength saving throw or be flung up to 3d4 × 10 feet away from the dragon, landing prone.

Fire Breath [rollable](Recharge 5–6);The dragon exhales fire in a 300-foot cone. Each creature in that area must make a DC 27 Dexterity saving throw, taking 119 (34d6) fire damage on a failed save, or half as much damage on a successful one. In addition, on a failure a creature gains a level of exhaustion due to the intense heat. cost 1 charge

Crushing Landing. If the dragon is flying, it can attempt to land forcefully in a space of its choice, even if that space is occupied by other creatures. When it does so, its movement speed is reduced to 0 until the end of the turn, and each creature in the dragon's space or within 30 feet of it, other than the dragon itself, must make a DC 27 Dexterity saving throw or take 26 (4d12) bludgeoning damage plus 21 (6d6) Force damage and be knocked prone.

Vacuum Sphere. The dragon exhales a bullet of concentrated air to a visible area within 300ft of it and summons a 40ft sphere of concentrated air all creature within the area make a DC20 Strength check or be pull into the centre of the sphere and take  90 (30d6) force damage on a successful check take half damage and they aren't moved

Reinforcement. The dragon can reinforce its body with energy adding 8d6 Fire or Force or Radiant damage area of effect of 10ft to any melee attack. cost 1 charge

Evaporate. When the dragon takes cold damage or is damaged by water created by a spell or natural effect, it can use its reaction to evaporate said water or any ice created by the cold-damaging effect. If it does so, it takes no damage instead, and the area within 60 feet of the dragon becomes heavily obscured by vapor until the start of its next turn.

Gravity Grab. When a being try's to fly or move away from the dragon within a 30ft are around it it can force them to make a DC 24 Strength check or they will go prone. cant be used if Core of Gravity is destroyed.

Legendary Action Uses: 3 . Immediately after another creature’s turn, the dragon can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each of its turns.

Frightful Presence. The dragon cause throughs around(200ft sphere ) it (below CR5)  (Wisdom Saving Thrown: DC 16) On a fail all being have the Frightened for 5 turns. 

Pounce. The dragon moves up to half its Speed, and it makes one Claw attack.