Adult Nightfury

Hold Breath. The dragon can hold its breath for 30 minutes. 

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

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: +11 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage.

Claw. Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 12 (2d6 + 5) slashing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 14 (2d8 + 5) bludgeoning 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 19 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.

Breath Weapons (Recharge 4–6). The dragon exhales an explosive blast of plasma, that travels up to 200 ft, then explodes in a 30 ft radius centered on the point of the blast. All creatures within the radius must make a DC 22 Dexterity save, taking 10d10 fire damage and 4d8 force damage on a failed save, or half damage on a successful save. If the blast crosses the space of any other creature, the blast of plasma explodes prematurely, dealing an additional 4d8 force damage to the creature hit by the blast on a failed DC 22 Strength save.  

Dive Bomb- The dragon spends its entire turn to dive from a great height, firing a blast of plasma at the vertex of the dive. This counts as using a Dash action, moving up to 150 ft and then launching the fire blast. The blast uses the same attack mechanics as the normal breath weapon, with an additional 4d8 force damage due to the dive. After the blast is launched, the dragon moves up to an additional 50 ft.  

Lightning Cloak- Once per day, the dragon can spend an action to cause bolts of lightning to arc across its body. It then turns invisible for up to a minute, or until it casts a spell, attacks, or loses concentration.

Command Dragons- As an action, the Nightfury can attempt to command any dragon. Any dragon with CR less than the Nightfury’s that is not hostile automatically listens and follows the command given. When the Nightfury targets a dragon that is hostile or has a CR greater than or equal to the Nightfury’s own CR, it may make a Charisma (Persuasion) or Charisma (Intimidation) check, opposed to the dragon’s Wisdom save, to bring that dragon under its command. Hostile dragons with a lower CR to the Nightfury have disadvantage on the save. The Nightfury can control as many hostile dragons of dragons with CR greater than or equal to its own as its Charisma modifier. The Nightfury has advantage on saves made to oppose other dragon’s Command Dragons ability.

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option 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.

Hide. The dragon takes the hide action. 

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 19 Dexterity saving throw or take 12 (2d6 + 5) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.