Ancient Temporal Dragon

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

Multiple Reactions. The dragon can take up to three reactions per round but only one per turn.

Temporal Awareness. The dragon can't be surprised, and it adds its Intelligence modifier to its initiative rolls.

Temporal Annihilation. When the dragon scores a critical hit on a creature, the target suffers 1 level of exhaustion and is magically aged. Roll a d10. On an even number, the target ages forward that many years; on an odd number, the target ages backward that many years.

Portent (3/Day). When the dragon finishes a Long Rest, roll three d20s and record the numbers rolled. The dragon can replace any attack roll, saving throw, or ability check made by it or a creature that it can see with one of these foretelling rolls. The dragon must choose to do so before the roll, and it can replace a roll in this way only once per turn. Each foretelling roll can be used only once. When the dragon finishes a Long Rest, it loses any unused foretelling rolls.

Spellcasting. The dragon casts one of the following spells, requiring no material components and using Intelligence as the spellcasting ability (Spell Save DC 23):
At will: shield, counterspell, temporal shunt
3/Day each: gravity sinkhole (5th-level version), pulse wave(7th-level version), slow
1/Day each: time stop, time ravage

Multiattack. The dragon uses its Frightful Presence. It then makes five attacks: one with its Bite and four with its Claws, or three attacks with its Astral Missile.

Bite. Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 14 (4d6) force damage.

Claw. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 17 (2d6 + 10) slashing damage.

Tail. Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage.

Astral Missile. Ranged Spell Attack: +18 to hit, range 120 ft., one target. Hit: 26 (4d8 + 10) force 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 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 dragon's Frightful Presence for the next 24 hours.

Temporal Breath (Recharge 5–6). The dragon exhales energy from the Astral Sea in a 100-foot Cone. Each creature in that area must make a DC 25 Constitution saving throw, taking 91 (18d10) force damage on a failed save, or half as much damage on a successful one. On a failure of 5 or more, a creature suffers 1 level of exhaustion and is magically aged. Roll a d10. On an even number, the target ages forward that many years; on an odd number, the target ages backward that many years.

Mote of Possibility. The dragon rerolls one attack roll it makes for the current turn.

Time Rush. The dragon takes the Dash action.

Displacement. When the dragon takes damage or fails a saving throw, it can magically teleport to an unoccupied space it can see within 500 feet of it. If it leaves the area of effect or the range of the source of the damage or saving throw, it suffers no damage or effects from that source.

Threads of Fate. When a creature the dragon can see makes an attack roll, ability check, or saving throw, the dragon forces them to roll an additional d20. The dragon chooses which of the d20 rolls the target must use.

Reactive Strike. At the end of another creature's turn, the dragon makes one Astral Missile attack.

Reactive Teleport. At the end of another creature's turn, the dragon magically teleports to an unoccupied space it can see within 500 feet of it.

Time Jump (Costs 2 Reactions). At the end of another creature's turn, the dragon shifts into the Ethereal Plane and travels in a straight line to an unoccupied space it can see within 80 feet of it. Each creature whose space the dragon passes through within the Ethereal Plane must succeed on a DC 25 Constitution saving throw or take 44 (6d12 + 10) force damage and be knocked Prone.