Valg King

Valg Royalty. The Valg king has advantage on saving throws against being charmed, and magic can't put the Valg king to sleep.

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

Spellcasting. The Valg king is an 14th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 18, +9 to hit with spell attacks). The Valg king has the following wizard spells prepared:

Cantrips (at will): chill touch, mage hand, minor illusion

1st level (4 slots): cause fear, longstrider, shield

2nd level (3 slots): darkness, mind spike, misty step

3rd level (3 slots): counterspell, fear, vampiric touch

4th level (3 slots): blight, phantasmal killer, summon greater demon

5th level (2 slots): enervation, wall of force

6th level (1 slot): mental prison

7th level (1 slot): finger of death

Longsword. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 13 (1d8 + 8) slashing damage, or 14 (1d10 + 8) piercing damage if used with two hands to make a melee attack.

Display Fear. Each creature that comes within 10 feet of the Valg king must succeed on a DC 18 Wisdom saving throw or take 20 (4d8) psychic damage and become Stunned 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, the creature takes half damage and is not Stunned. On a successful save or the effect ends for it, the creature is immune to the Valg king's Display Fear for the next 24 hours.

The Valg king 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 Valg king regains spent legendary actions at the start of its turn.

Summon Allies (1 action). The Valg king reaches into the darkness and calls for three quasits to appear in an unoccupied space as his allies. The quasits can be summoned in any area of dim light or darkness within sight of the Valg king. They have their own initiative but obey all of the Valg king's commands.

Umbrastep(2 actions). The Valg king possesses the ability to manipulate darkness and shadows and thus steps into his own shadow and reappears out of another shadow in sight of the original position and within 60 ft. 

Mind Manipulation (3 actions). The Valg king penetrates the mind of his target and begins combing through the target's worst memories, forcing the target to relive each one. The target must succeed on a DC 18 Intelligence saving throw or take 30 (10d6) psychic damage and is Stunned 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.