Archduke Glasya of Malbolge

Devil's Sight. Magical darkness doesn't impede Glasya's darkvision.

Confusion Aura. Any creature hostile to Glasya that starts its turn within 20 feet of Glasya must make a DC 21 Charisma saving throw, unless Glasya is incapacitated. On a failed save, the creature suffers the affects of the confusion until the start of its next turn. If a creature's saving throw is successful, the creature is immune to Glasya's Confusion Aura for the next 24 hours.

Innate Spellcasting. Glasya's innate spellcasting ability is Charisma (spell save DC 25). She can innately cast the following spells, requiring no material components:

At will: alter self (can become Medium when changing her appearance), geas, greater invisibility, major image, charm monster, contagion

3/day each: dominate monster, hold monster, polymorph

1/day: feeblemind, finger of death

Legendary Resistance (3/Day). If Glasya fails a saving throw, she can choose to succeed instead.

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

Regeneration. Glasya regains 20 hit points at the start of her turn. If she takes radiant damage, this trait doesn't function at the start of her next turn.  If Glasya loses a limb or body part, the lost portion regrows in 1d6 minutes. Glasya can reattach the severed member instantly by holding it to the stump. Glasya dies only if she starts her turn with 0 hit points and doesn't regenerate.

Multiattack. Glasya attacks twice with her whip. She can substitute Touch of Death for one of these attacks.

Whip of Despair. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 22 (2d4 + 8) piercing damage and the target must make a DC 21 Constitution saving throw, taking 14 (4d6) poison damage on a failed save and being stunned for one round as their mind is filled with utter hopelessness, or half as much damage and no stun effect on a successful save. Creatures that are immune to the frightened condition are not affected by the stun. The target's hit point maximum is reduced by an amount equal to the necrotic damage taken, and Glasya regains hit points equal to that amount. The reduction lasts until the target finishes a long rest. The target dies if this effect reduces its hit point maximum to 0, being reborn in Malbolge as a fiend.

Bite. Melee Weapon Attack: +16 to hit, reach 5 ft., one target. Hit: 22 (2d6 + 8) piercing damage. The target must succeed on a DC 21 Constitution saving throw or become poisoned. While poisoned in this way, the target can't regain hit points, and it takes 35 (10d6) poison damage at the start of each of its turns. The poisoned target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Summon Fiends (1/Day). Glasya summons 5d4 erinyes or 6d6 succubi without fail. The summoned fiends appears in an unoccupied space within 60 feet of the archduke, act as an ally of their summoner, and can’t summon other fiends. They remain until they die, or until Glasya dismisses some or all of them as an action.

Touch of Death (Recharge 5–6). Glasya targets one humanoid she can see within 30 feet of her. The target must succeed on a DC 21 Constitution saving throw or become infected with a disease on a failed save. This disease only takes affect after the target creature long rests. Corruption fills the creatures mind and body as both begin to deteriorate. During this time the target is poisoned and every time the creature finishes a long rest it takes 13 (2d12) necrotic damage that reduces the creatures maximum hit points by the damage taken.

Teleport. Glasya magically teleports, along with any equipment she is wearing or carrying, up to 120 feet to an unoccupied space she can see.

Glasya 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. Glasya regains spent legendary actions at the start of her turn.

Enchantress (Costs 2 Actions). Glasya casts any one of her spells on her innate spellcasting list.

Fearful Speech. By describing the tortures that will befall others, Glasya can force a DC 18 Wisdom saving throw. If the target fails, they are frightened of her or a subject of her choice for one minute. This effect can repeat indefinitely until the target succeeds on the saving throw, at which point it is immune to the effects of her terrifying words for 24 hours.

Teleport. Glasya uses her Teleport action.

Whip of Despair. Glasya uses her Whip of Despair action.