Avatar of Nyarlathotept

Bringer of Chaos. The Avatar of Nyarlathotept emits an aura of unrest and discontent. All creatures within 60 ft. of the Avatar that can see or hear it must make a DC 26 Charisma saving throw or be unable to benefit from positive effects (including healing and hit point modifications) administered by any creature other than itself for the next 24 hrs. Creatures may repeat this save at the end of their turns, ending the effect on a success. Creatures that succeed this saving throw are immune to this trait's effect for the next 24 hrs.

Crawling Chaos. The Avatar cannot be detected by any divination magic unless it wishes to and it can pass through any space more than 1 inch wide and 1 inch tall. The Avatar must move each turn and end it's turn more than 10 feet away from where it began it's turn or it takes 1d10 force damage.

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

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

Shatter Order. The Avatar of Nyarlathehotept makes two attacks with Grip of Madness and uses Gaze unto the Unknown. The Avatar can substitute any number of its Grip of Madness attacks with Cosmic Static

Grip of Madness. Melee Weapon Attack: +13 to hit, reach 10 ft., 1 target. Hit: 19 (4d6 + 5) slashing damage. The target must make a DC 26 Wisdom saving throw or be forced to spend it's reaction to move up to it's speed towards one creature of the Avatar's choice and make an attack against that creature. 

Cosmic Static. Ranged Weapon Attack: +18 to hit, range 120 ft., 1 target. Hit: 19 (2d8 + 10) lightning damage and the target must succeed a DC 26 Constitution saving throw or be blinded until the end of it's next turn. Up to two creatures within 10 ft. of the target take 9 (2d4) lightning damage

Gaze Unto the Unknown. One creature the Avatar can see within 120 ft. must make a DC 26 Wisdom saving throw or be trapped in an illusory realm of the Avatar's design, unable to see or hear anything other than what the Avatar allows.

Crawl Through Chaos. The Avatar of Nyarlathotept teleports to a point within 10 feet of a creature that has failed a saving throw controlled by the Avatar within the last two rounds. That creature takes 10 (2d10) force damage.

1,000 Forms. The Avatar assumes a new form. Aside from his size, his statistics are the same in each form. Any creature that can see The Avatar must make a DC 23 Intelligence saving throw or take 9 (2d8) psychic damage.

Entropy Rebounding. When a creature attacks The Avatar of Nyarlathotept, it may use it's reaction to impose disadvantage on the attack. If the attack misses, the creature takes 2d10 force damage and The Avatar gains advantage on it's next attack, which will deal an additional 2d10 force damage. 

The Avatar can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The Avatar regains spent legendary actions at the start of its turn.

Invite Unreality. The Avatar opens a portal into the Far Realms; All creatures within 20 feet of a point that the Avatar designates within 120 ft that it can see must make DC 26 Intelligence saving throw, taking 21 (6d6) psychic damage and be frightened until the end of its next turn on a failed save or half damage only on a successful save.

Sanity Rending Magic (Costs 2 Actions). The Avatar casts one of the following spells without needing any material components using Charisma as it's spellcasting modifier (Spell save DC 26, Spell attack modifier +18): Synaptic Static, Tasha's Mind Whip, Befuddlement (Once per short rest), Mental Prison (Once per short rest), Psychic Scream (Once per short rest).

Blast Sanity (Costs 2 Actions). The Avatar fixes one creature that it can see within 60 ft with it's sanity blasting  gaze. The creature must make a DC 26 Intelligence saving throw. On a failed save the creature takes 6d10+10 psychic damage, if  the creature is already under the effect of Gaze into the Unknown, or Bringer of Chaos, the creature is rendered insane, unable to communicate in any way for an hour, repeating saves at the end of each turn. On a successful save, the creature takes half damage only.