Psychosis.  Pure Insanity renders Yawa immune to Psychic damage

Pseudo-Deific. Yawa can cast any spell without using materials

Yawa. Upon being reduced to 0hp, Yawa transforms into Yawa (Phase 3)

Spellcasting. Yawa is a 6th-level spellcaster. His spellcasting ability is Charisma. Yawa has following Warlock spells prepared:
Cantrips: Eldritch Blast, Chill Touch

1st level: Hellish Rebuke, Expiditious Retreat

2nd level: Ray of Enfeeblement, Shatter 

3rd level: Counterspell, Vampiric Touch

4th level: Blight, Hallucinatory Terrain

6th level: Eyebite, Circle of Death

Klimeth Summon. Yawa summons 1d4 Klimeth to the battlefield

Lightning Claws. Melee Weapon Attack: +2 to hit, reach 5 ft., 1 target. Hit: 1d8 Lightning damage, 1d8 Slashing damage.

Flame Spears. Ranged Weapon Attack: +2 to hit, range 45 ft., 3 target. Hit: 1d6 Fire damage, 1d6 Piercing damage (per target)

Lightning Jab. Upon being struck with a close range melee attack, Yawa can jab the assailant with his claws, dealing 3d4 - 1 Lightning damage

Flame Cannon (Costs 2 Actions). Yawa's spears rotate around eachother, forming a ball of intense flames, which is launched at a single target, dealing 2d20  Fire damage.