Aspect of Angdar

Domain Expertise. The aspect has Expertise in Arcana.

Weavespeaking. The aspect can cast the Wish spell as a Ritual, but only to duplicate other spells.

Runic Revelation (Recharges after a Short or Long Rest). If the aspect would be reduced to 0 hit points, his current hit point total instead resets to 500 hit points, he recharges his Breath Weapon, and he regains any expended uses of Spellcasting and Legendary Resistance. Additionally, the aspect can now use the options in the “Mythic Actions” section for 1 hour. Award a party an additional 155,000 XP (310,000 XP total) for defeating the aspect of Angdar after his Runic Revelation activates.

Legendary Resistance (5/Day). If the aspect fails a saving throw, he can choose to succeed instead.

Multiattack. The aspect makes one Bite attack, one Claw attack, and one Tail attack, or he can forego one of those attacks to use his Psychic Blast.

Bite. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 21 (2d12 + 8) piercing damage plus 22 (4d10) force damage.

Claw. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 19 (2d10 + 8) 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 aspect can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (2d12 + 8) bludgeoning damage. If the target is a creature, it must succeed on a DC 25 Strength saving throw or be knocked prone.

Psychic Blast. Wisdom Saving Throw: DC 27, range 120 ft., one creature. Failure: The creature is charmed and stunned for 1 minute or until it takes any damage. A creature can repeat this save at the end of each of its turns, ending all effects on a success. Success: The creature takes 13 (2d12) psychic damage and is frightened of the aspect until the start of the aspect's next turn.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Intelligence as the spellcasting ability (spell save DC 27, +19 to hit with spell attacks):

At Will: Detect Magic, Chromatic Orb (4th Level version), Invisibility, Life Transference, Shapechange (Beast, Dragon, or Humanoid form only, no Temporary Hit Points gained from the spell, and no Concentration or Temporary Hit Points required to maintain the spell)
3/Day Each: Banishment, Magic Circle, Scatter
2/Day Each: Fireball, Lightning Bolt, Vitriolic Sphere, Ice Storm
1/Day Each: Prismatic Wall, Disintegrate,  Wish

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

Umbral Breath. The aspect exhales the dark void of the Umbral Plane in a 300-foot cone. Each creature concentrating on a spell in that area must make DC 25 Concentration check, and each ongoing spell in or originating from the area that is not being maintained by Concentration or originating from an Artifact is automatically dispelled. Other magical effects in the area, including the magical properties of magic items, are suppressed until the beginning of the aspect's next turn.

Aether Breath. The aspect exhales prismatic aether in a 300-foot cone. Each creature in that area must make a DC 25 Dexterity saving throw, taking 66 (12d10) force damage on a failed save, or half as much damage on a successful one.

Quick Thinking. The aspect can take the Study action as a bonus action.

Psychic Step. The aspect magically teleports to an unoccupied space it can see within 60 feet of it.

The aspect 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 aspect regains spent legendary actions at the start of his turn.

Attack. The aspect makes one Claw or Tail attack.

Furious Bite (Costs 2 Actions). The aspect makes one Bite attack. If the attack hits a creature, the target must succeed on a DC 26 Wisdom saving throw or become frightened of the aspect until the end of the target’s next turn.

Spellcasting (Costs 3 Actions). The aspect uses his Spellcasting feature.

If the aspect’s Runic Revelation trait has activated in the last hour, he can use the options below as legendary actions.

Immunity. The aspect gains immunity to one damage type of his choice until he uses this option again.

Spellcasting (Costs 2 Actions). The aspect uses his Spellcasting feature.

Psychic Wave (Costs 3 Actions). The aspect uses his Psychic Blast attack on any number of creatures within range.