Beelzebub (Lord of Gluttony)

Devil's Sight. Magical darkness doesn't impede the archdevil's darkvision.

Abyssal Weapons. The archdevil's weapon attacks are magical and deal an extra 5d8 necrotic damage on a hit (included in the attacks).

Regeneration. The archdevil regains 25 Hit Points at the start of its turn if it has at least 1 hit point. Although his regeneration was supernaturally fast, allowing him to regrow body parts in a few minutes and reattach severed limbs, if Beelzebub takes radiant damage or damage from a holy weapon, this trait doesn't function at the start of his next turn.

Terrifying Appearance. When a creature that can see the entity starts its turn within 60 feet of it, they must make a DC 18 Wisdom saving throw. On a failed save, the creature is frightened 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 or the effect ends for it, the creature is immune to the entity’s Terrifying Appearance for the next 24 hours.

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

Innate Spellcasting. The archdevil's spellcasting ability is Charisma (spell save DC 28). The archdevil can innately cast the following spells, requiring only verbal components:

Cantrips: Chill Touch,
At will: Detect Evil and Good, Suggestion, Summon Fiend, Clairvoyance, Fear,
Ray of Enfeeblement, Insect Plague, Invisibility, Bestow Curse,
Summon Undead, Control Flames, Fireball, Wall of Fire,
3/day each: Symbols, Create Homunculus, Create Magi, Circle of Death, Disintegrate,
Eyebite, Create Undead, Danse Macabre, Enemies Abound,
1/day each: Unholy Words, Wish, Power Word Kill, Maddening Darkness, Mirage Arcane,

Multiattack. The archdevil can take two attack actions.

Raptorial Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 18 (3d8 + 5) piercing damage plus 22 (5d8) necrotic damage.

Insect control and summon. Most note-worthy, his gargantuan clouds of flesh-devouring flies, an ability he has to wait a few dozen seconds to reuse. Although the flies normally dispersed after being spewed, he could cause them to swarm and envelop his form if he so desired for about a minute, protecting him from harm as the flies don't attack his grotesque mass.

Horn of Darkness. While holding the apocalyptic instrument, you can use an action to blow the horn to cause a swarm of harmless flying insects or 1d6 of one chosen animal to spread out in a 30-foot radius from you. The insects remain for 10 minutes, making the area heavily obscured for creatures other than you. The swarm moves with you, remaining centered on you. A wind of at least 10 miles per hour disperses the swarm and ends the effect. The animals remain for 10 minutes, remaining within a 60-foot radius around the blower of the trumpet. They can make independent actions after having received orders from their master. Upon blowing the horn again, you can cause them to die prematurely.

Devil Trigger. Starting at 3rd level, you can use your action to unleash the divine energy within yourself, causing your eyes to turn into pools of darkness. The instant you transform, other creatures within 10 feet of you that can see you must each succeed on a Charisma saving throw (DC 8 + your proficiency bonus + your Charisma modifier) or become frightened of you until the end of your next turn.

Your transformation lasts until you end it as a bonus action. During it, once on each of your turns, you can deal extra necrotic damage to one target when you deal damage to it with an attack or a spell. The extra necrotic damage equals your level.

Once you use this trait, you can't use it again until you finish a long rest.

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

Cantrip. The Archdevil casts a cantrip.

Blinding Swarm. A giant cloud of flies swarm magically around the creature. Each target within 5 feet of the creature must succeed on a DC 16 Constitution saving throw or be blinded until the end of the target’s next turn.

Frightening Gaze (Costs 2 Actions). The Archdevil fixes its gaze on one creature it can see within 10 feet of it. The target must succeed on a DC 18 Wisdom saving throw against this magic or become frightened for 10 rounds. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to the Archdevil's gaze for the next 24 hours.

Locust dodge (Costs 2 Actions). The creature magically transforms into a whirlwind of sand, moves up to 60 feet, and reverts to its normal form. While in whirlwind form, the creature is immune to all damage, and it can’t be grappled, petrified, knocked prone, restrained, or stunned. Equipment worn or carried by the creature remains in its possession.

Disrupt Life (Costs 3 Actions). Each non-undead creature within 20 feet of the Archdevil must make a DC 18 Constitution saving throw against this magic, taking 21 (6d6) necrotic damage on a failed save, or half as much damage on a successful one.