Avatar of Hastur

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

Innate Spellcasting. The Avatar of Hastur is a 15th-level spellcaster. Its spellcasting ability is Charisma (spell save DC 18, +12 to hit with spell attacks). The Avatar of Hastur can innately cast the following spells, no spell components required:

At will: Counterspell, Dispel Magic, Dream, Ray of Enfeeblement, Sending, Suggestion, Fly, Tongues, True Seeing, Eldritch Blast, Hold Person
3/day: Symbol, Mass Suggestion, Banishment
1/day: Feeblemind, Project Image, Teleport

Multiattack. The Avatar of Hastur can use the Touch of the Yellow King or Gaze of the Yellow King once each per turn.

Touch of the Yellow King. Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 27 (4d10 + 7) Psychic damage. The target must succeed on a DC 16 Wisdom saving throw or be confused until the end of its next turn. A confused creature can't take reactions and must roll a d8 at the beginning of its next turn. On a roll of 1 or 2 the creature cannot take an action. On a roll of 3 or 4 it makes a random melee attack against a creature within reach, if not creature is within reach it cannot take an action or move. On a roll of 5 or 6 it uses its action to dash and moves its full movement in a random direction. On a roll of 7 or 8 it makes an attack against itself.

Gaze of the Yellow King. Ranged Spell Attack: +16 to hit, range 120 ft., two targets. Hit: 22 (3d8 + 8) psychic damage. The Avatar of Hastur does not suffer disadvantage if using this while within 5 ft. of an enemy.