Dranarut

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

Immutable Form. The dranarut is immune to any spell or effect that would alter its form.

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

Innate Spellcasting. The dranarut's spellcasting ability is Charisma (spell save DC 22, +14 to hit with spell attacks). The dranarut can innately cast the following spells, requiring no material components:
At will: detect magic, dispel magic, plane shift, dimension door
3/day each: antimagic field
1/day each: hold person, hold monster 

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

Frightful Presence. Each creature of the dranarut's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 22 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 dranarut’s Frightful Presence for the next 24 hours.

Bite. Melee Weapon Attack: +16 to hit, reach 10 ft., 1 target. Hit: 25 (3d10 + 9) piercing damage plus 10 (3d6) force damage. Miss: The target takes 7 (2d6) force damage.

Claw. Melee Weapon Attack: +16 to hit, reach 5 ft., 1 target. Hit: 23 (4d6 + 9) slashing damage. 

Tail. Melee Weapon Attack: +16 to hit, reach 15 ft., 1 target. Hit: 22 (3d8 + 9) bludgeoning damage. 

Force Breath (Recharge 5-6). The dranarut exhales a wave of force in a 60-foot cone. Each creature in that area must make a DC 22 Dexterity saving throw, taking 70 (20d6) force damage on a failed save, or half as much damage on a successful one.

The dranarut 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 dranarut regains spent legendary actions at the start of its turn.

Detect. The dranarut makes a Wisdom (Perception) check.

Tail Attack. The dranarut makes a tail attack.

Wing Attack (Costs 2 Actions). The dranarut beats its wings. Each creature within 10 feet of the dranarut must succeed on a DC 22 Dexterity saving throw or take 23 (4d6 + 9) bludgeoning damage and be knocked prone. The dranarut can then fly up to half its flying speed.