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

Jaw Mandibles. The lower jaw splits down the middle and two praying mantis like mandibles unfold and extends out. The dragon has advantage on all grapple checks made with its mouth. The dragon can make bite attacks agains creatures that are grappled in its mouth.

Scrying Eye Recharge (5-6). An invisible scry sensor is constantly projected above the dragon. Any ability that would reveal a Scrying sensor will reveal an eye-like orb that hovers 10 feet above the center of the dragon. It can be dispelled just as if it was a 5th level spell. If a Scrying Eye is not present at the start of the dragon's turn one appears on a successful recharge, no action cost. 

Mind Sight. The dragon can see any intelligent creature out to a distance of 40 feet. Any creature with an Intelligence score of 4 or more is detectable by the dragon regardless of magic or cover from the dragon. 

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

Bite. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) piercing damage.

Claw. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.

Reel. The dragon pulls a creature grappled by its Tongue Skewer up to 20 feet straight towards it.

Frightful Presence. Each hostile creature the dragon is aware of that is within 120 feet of the dragon must succeed on a DC 18 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.

Tongue Skewer. The dragon spits out a long sinewy tongue ending in a boney barb, 40-foot range one target large or smaller. The target takes 10d6 piercing damage and is grappled, if the target makes a successful DC 18 Dexterity save it takes half damage and is not grappled. Escape DC 18.

While a creature is grappled by the tongue skewer the dragon cannot make bite attacks.

Crushing Jaws. If the dragon starts its turn with a creature in its mouth that creature is  grappled.The dragon can make a bite attack as a bonus action against the grappled creature with advantage. 

The dragon has a +13 to its Strength(Athletics) checks.

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.

Psychic Wounds. The dragon deals 4d6 psychic damage to any creature it can detect with is Mind Sight special ability that was damaged by the dragon on its last turn. 

Reel (Costs 2 Actions). The dragon pulls a creature grappled by its Tongue Skewer up to 20 feet straight towards it. 

Tongue Skewer (Costs 3 Actions). The dragon makes a Tongue Skewer attack.