Chorranathau the inscrutable

Keen Hearing and Smell. Chorranathau  has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Inscrutable. Chorranathau  is immune to any effect that would sense his emotions or read his thoughts, as well as any divination spell that he refuses. Wisdom (Insight) checks made to ascertain the Chorranathau's intentions or sincerity have disadvantage.

Draconic toxin. When Chorranathau makes a bite attack the target must make a dc 21 Constitution saving throw or take 25 (5d10) poison damage and make another Constitution saving throw or have their maximum hit points reduced by 4 (2d4) and if the target is reduced to 0 hit points by the reduction of maximum hit points the target dies (included in attack). 

Devastating critical. When Chorranathau scores a critical it deals 3 times the normal damage and deals an additional 9 (3d6) damage. 

Sound imitation. Chorranathau can mimic any sound or voice they have heard with a dc 15 deception check. 

Legendary Resistance (3/Day). If Chorranathau fails a saving throw, he can choose to succeed instead.

Magic Weapons. Chorranathau's weapon attacks are magical.

Innate Spellcasting. Chorranathau’s innate spellcasting ability is Wisdom (spell save DC 20). Chorranathau can innately cast the following spells, requiring no material components or somatic components. 

At will: dominate monster, detect magic, identify

3/day each: scrying 

2/day each: shield, telekinesis

1/day: Dispel magic, globe of invulnerability, counterspell

Multiattack. Chorranathau can use his Frightful Presence. It then makes three attacks: one with his bite and two with his claws.

Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 22 (3d8 + 10) piercing damage and the target must make a dc 21 Constitution saving throw or take 25 (5d10) poison damage and make another Constitution saving throw or have their maximum hit points reduced by 4 (2d4) and if the target is reduced to 0 hit points by the reduction of maximum hit points the target dies. 

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 17 (2d6 + 10) slashing damage.

Tail. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 22 (4d6 + 10) slashing damage.

Frightful Presence. Each creature of Chorranathau’s choice that is within 120 feet of Chorranathau and aware of him must succeed on a DC 21 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 Chorranathau’s Frightful Presence for the next 24 hours.

Twist of fates. Chorranathau can use on of the following options by looses his insight bonus for the following 1d4 rounds:

• When Chorranathau is targeted by a multi targeted spell it can make a Dexterity saving throw to avoid the attack and take no damage. 
• Instead of making an attack of opportunity against the target Chorranathau can choose to force them to make a dc 21 Strength save or be knocked prone. 

Chorranathau 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. Chorranathau regains spent legendary actions at the start of his turn.

Detect. Chorranathau makes a Wisdom (Perception) check.

Tail Attack. Chorranathau makes a tail attack.

Wing Attack (Costs 2 Actions). Chorranathau beats his wings. Each creature within 15 ft. of Chorranathau must succeed on a DC 22 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. Chorranathau can then fly up to half his flying speed.