Ageless Aegis. The dragon's body is infused with Adamantine, it takes only normal damage from Critical hits and its Claws are critical hits on a roll of 19-20.

Magic Weapons. The dragon's weapon attacks are magical. 

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

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

Multiattack. The dragon makes two claw attacks.

Claw. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 17 (2d10 + 6) slashing damage.

Tail. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 15 (2d8 + 6) bludgeoning damage.

Eon Pulse. Each creature within 15 feet of the dragon must succeed on a DC 18 Dexterity saving throw or take (6d6) force damage on a failed save, or half as much damage on a successful one. Every creature that fails the save is pushed 15 feet away from you and is knocked prone.

Roar of Time (Recharge 6). The dragon emits a roar, releasing a stream of compressed time. Each creature in a 120-­foot line that is 5 feet wide must make a DC 18 Constitution saving throw, taking (10d12) necrotic damage on a failed save, or half as much damage on a successful one. If the save fails, the target also ages to the point where it has only 30 days left before it dies of old age. In this aged state, the target has disadvantage on attack rolls, ability checks, and saving throws, and its walking speed is halved. Each successive time it roars before finishing a long rest, the roar is louder and the effect is different, as detailed below. Each creature within 500 feet of the dragon and able to hear the roar must also make a saving throw.

First Roar. Each creature that fails a DC 18 Wisdom saving throw is frightened for 1 minute. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Second Roar. Each creature that fails a DC 18 Wisdom saving throw is deafened and frightened for 1 minute. A frightened creature is paralyzed and can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Third Roar. Each creature makes a DC 18 Constitution saving throw. On a failed save, a creature takes 44 (8d10) thunder damage and is knocked prone. On a successful save, the creature takes half as much damage and isn't knocked prone.

Time Walk. The Dragon briefly stops the flow of time for everyone but itself. No time passes for other creatures, while it takes 1d4-2 turns in a row, during which it can use actions and move as normal, it can not attack or affect other creatures during these extra turns. 

Temporal Shunt. The Dragon causes a creature it can see to slip thru time. As a Reaction when it sees the creature make an attack roll or starts to cast a spell. The triggering creature, must succeed on a DC 18 Wisdom saving throw or vanish, being thrown to another point in time and causing the attack to miss or the spell to be wasted. At the start of its next turn, the target reappears where it was or in the closest unoccupied space. The target doesn’t remember being affected by this 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.

Tail Attack. The dragon makes a tail attack.

Eon Pulse (Costs 2 Actions). The dragon releases an Eon Pulse attack.

Time Heals All Wounds (Costs 3 Actions). The Dragon heals itself within a time bubble. The Dragon heals 1 Condition that is effecting it or 50 Hit Points.