Camazotz

Demonic Restoration. If Camazotz dies outside the Abyss, his body dissolves into ichor, and he gains a new body instantly, reviving with all his Hit Points somewhere in the Abyss.

Fire Aura. At the end of each of Camazotz's turns, each creature of his choice in a 5-foot Emanation originating from the azer takes 7 (2d6) Fire damage unless Camazotz has the Incapacitated condition.

Keen Hearing. Camazotz has Advantage on Wisdom (Perception) checks that rely on hearing.

Legendary Resistance (Costs 2 Souls). If Camazotz fails a saving throw, he can choose to succeed instead.

Magic Resistance. Camazotz has Advantage on saving throws against spells and other magical effects.

Soul Count. Camazotz can consume a number of souls he has consumed to power certain effects, such as his Legendary Resistance ability. Camazotz has consumed 7 (3d4) souls before the beginning of combat.

Multiattack. Camazotz makes one Bite attack. He then makes two Claw attacks, or three Claw attacks if he has used Hasten this turn.

Bite. Melee Attack Roll: +17, reach 5 ft. Hit: 38 (8d6 + 10) Piercing damage plus 7 (2d6) Fire damage, and the target has the following effect. Constitution Saving Throw: DC 22. Failure: The target's Strength score is reduced by 1d4. The target dies if this reduces its Strength to 0. Otherwise, the reduction lasts until the target finishes a Long Rest. A Humanoid that dies from this reduction rises 1d4 days later as a vampire under Camazotz’s control, unless the Humanoid is restored to life or its body is destroyed. Camazotz can have no more than five vampires under his control at a time.

Claw. Melee Attack Roll: +17, reach 10 ft. Hit: 31 (6d6 + 10) Slashing damage plus 7 (2d6) Fire damage.

Fire Breath (Recharge 5–6). Dexterity Saving Throw: DC 22, each creature in a 30-foot Cone. Failure: 33 (6d10) Fire damage and 33 (6d10) Necrotic damage. Success: Half damage.

Call Bats (3/Day). Camazotz magically calls 4d6 giant bats or swarms of bats, or 2d6 vrocks. The called creatures arrive in 1d4 rounds, acting as allies of Camazotz and obeying his telepathic commands. The creatures remain for 1 hour, until Camazotz dies, or until Camazotz dismisses them as a Bonus Action. Camazotz can have no more than twenty four giant bats or swarms of bats, or twelve vrocks under his control at a time. 

Spellcasting. Camazotz casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 22):

At Will: Darkness, Detect Evil and Good, Dispel Magic

3/Day: Dominate Person

1/Day: Incendiary Cloud

Change Shape. Camazotz magically shape-shifts into a Large giant bat covered in smoldering ashes, or back into his true form, which is a Fiend. His statistics, other than his size, are the same in each form. Any equipment he is wearing or carrying transforms with him. He reverts to his true form if he dies.

Hasten (Costs 2 Souls). Camazotz takes the Dash and Disengage actions.

Soul Devourer. Trigger: Camazotz reduces a creature who isn’t a Construct or an Undead to 0 Hit Points. Response -- Wisdom Saving Throw: DC 15. Failure: Camazotz consumes the creature’s soul and adds 1 to his soul count. A creature whose soul is consumed in this way immediately dies, and it can’t be restored to life by any means short of a Wish.

Legendary Action Uses: 3. Immediately after another creature’s turn, Camazotz can expend a use to take one of the following actions. Camazotz regains all expended uses at the start of each of his turns.

Reposition. Camazotz moves up to his Walking Speed, or flies up to half his Fly Speed, without provoking Opportunity Attacks.

Douse the Sun. Camazotz uses Spellcasting to cast Darkness or Detect Magic. Camazotz can't take this action again until the start of his next turn.

Flight of the Fury. Dexterity Saving Throw: DC 22, each creature within 10 feet of Camazotz. Failure: 14 (4d6) Fire damage, and the target is Prone. Failure or Success: All mundane light sources within 10 feet, and instances of Light and Dancing Lights end in the area.