Legendary Resistance (4/Day). If the Acient One fails a saving throw, it can choose to succeed instead.

Call of the Gods (Recharges after a Short or Long Rest) If the Acient One would be reduced to 0 hit points, its current hit point total instead resets to 500 hit points, it recharges its Breath Weapon, and it regains any expended uses of Legendary Resistance. Additionally, the Ancient One can now use the options in the “Mythic Actions” section for 1 hour. Award a party an additional 120,000 XP (240,000 XP total) for defeating the Ancient One after its Call of the Gods activates.

Unusual Nature. The Ancient One doesn’t require food or drink.

Multiattack: The Ancient One makes one Bite attack and two Claw attacks.

Bite Melee Weapon Attack: +18 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 13 (2d12) necrotic damage.

Claw Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 19 (2d8 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and is restrained until this grapple ends. The Ancient One can have only one creature grappled in this way at a time.

Tail Melee Weapon Attack: +18 to hit, reach 20 ft., one target. Hit: 21 (2d10 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 24 Strength saving throw or be knocked prone.

Breath Weapon (Recharge 5–6): The Ancient One uses one of the following breath weapons:

Dark Pulse: The Ancient One ejects a dark energetic aura from the centre of his body in a 120-foot sphere. Each creature must make a DC 24 Constitution saving throw, on a failed save each target take 75 (5d20 + 20) necrotic damage and is now frightened for 1 minute. On a successful save the target take half damage and ist stunned for 1 round.

Rotten Earth: The Acient One exhales a gray / purplish flame in a 300-foot cone. Each creature must make a DC 24 Constitution saving throw, on a failed save each target takes 85 (10d10 + 25) necrotic damage and is poisend, on a successful save each target takes half damage and is poisend. The ground is now difficult terrain and each creature ending its turn in takes 1d12 necrotic damage.

Change Shape: The Ancient One magically transforms into any creature that is Medium or Small, while retaining its game statistics (other than its size). This transformation ends if the dragon is reduced to 0 hit points or uses its action to end it.

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

Attack The Ancient One makes one Claw or Tail attack.

Wing Attack The Ancient One beats its wings. Each creature within 30 feet of it must succeed on a DC 26 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. The Ancient One can then fly up to half its flying speed.

Guardians of the Undead (Costs 2 Actions) The Ancient One Summons 1 Adult Blue Dracolich and 1 Adult Blue Dracolich to help it in battle.

Mythic Actions If the Ancient Ones Call of the Gods trait has activated in the last hour, it can use the options below as legendary actions.

Bite The Ancient One makes one Bite attack.

The Ancient Roar (Costs 2 Actions) The Ancient One unleashes a powerful magical roar. Each creature in a 150-foot-radius sphere centred on the Ancient One must succeed on a DC 26 Constitution saving throw or take 30 (5d10) Necrotic damage and be incapacitated until the end of its next turn.