Vampire Dragon

Regeneration: The vampire regains 20 hit points at the start of its turn if it has at least 1 hit point remaining. If it receives radiant damage, is in running water, or is harmed by holy water, this effect is not activated on its next turn. 

Legendary Resistance (2/day): If the dragon fails a saving throw, it may instead choose to succeed it. 

Toxic Breathing: If any creature is capable of inhaling while 5 feet in front of the dragon, it must make a dc 20 constitution saving throw or take 1 level of exhaustion and 12 (3d4+4) Poison Damage. On a successful save, the creature is not affected.

Multi-attack: The dragon may attack twice each turn, one of which must be a bite attack.

Bite: Melee Weapon Attack: +11 to hit, reach 10 ft., 1 target. Hit: 21  (3d8 + 4) Piercing damage. The creature must make a Constitution saving throw or take 9 (1d8+1) Necrotic damage. The dragon gains twice as much life equal to the necrotic damage dealt unless it has been dealt radiant damage, is in running water or was harmed by holy water in the past turn order. This 

Wing Slash (unarmed strike): Melee Weapon Attack: +9 to hit, reach 15 feet, any creature in range, Hit: 12 (2d8+3) Slashing damage. When used as a legendary action, this attack pushes creatures back equal to the damage they take.

Screech (3/day): The dragon lets out a loud screech, causing any creature without ear coverings to become deafened. This effect ends after a long rest, or if more than 20 hit points are restored to that creature.

As a reaction, the dragon may fly downwards if it is in the air and a projectile is going at it (including magic projectiles) and it will dodge the projectile if possible as well as deal 7 (1d6+4) Blueodgoning damage for every 10 feet it falls to any creature below it. The damage is halved rounded down for every 5 feet away the creature is up until 15 feet, where the damage is not dealt. All creatures in this radius will be pushed back any number of feet equal to the amount of damage they took. If they succeed in a dc 18 dexterity saving throw, they can dodge the knockback, or a dc 21 constitution saving throw may be taken to avoid being knocked back.

Legendary Actions: The dragon may take 2 legendary actions chosen from below. Both may be taken at the same time, but can also be taken at different times, and can only be taken at the end of another creature's turn. Only one action may be used in each turn order.

Breath Fire (Costs 2 Actions): The dragon breathes a flame at any creature in front of it within a 15-foot length. The creature must make a DC 18 dexterity or constitution saving throw or take 32 (4d12+4) Fire Damage and be set on fire for 1d4+2 turns for 16 (2d12+3) damage at the start of each turn. On a successful save, the damage is halved and the creature is not set on fire. The fire is not magical, and cannot be reflected or absorbed by magical items or magic.

Flight (Costs 1 Action): The dragon flies upwards into the air equal to its movement and hovers there until the start of its next turn. While in flight, if it is restrained or mounted then its movement speed is halved. 

Wing Slash (unarmed strike) (Cost 1 Action): Melee Weapon Attack: +9 to hit, reach 15 feet, any creature in range, Hit: 12 (2d8+3) Slashing damage. When used as a legendary action, this attack pushes creatures back equal to the damage they take.