Alastor, The Broadcast Demon

Always On Air. The Broadcast Demon is constantly surrounded by faint music, static, or applause. Creatures of his choice within 60 ft have disadvantage on saving throws against charm and illusion effects.

Broadcast Authority.  His voice overrides free will. Creatures charmed by the Sovereign cannot target him with attacks or harmful effects and treat his commands as a reasonable request.

Audience Participation. The Broadcast Demon feeds on attention. When a creature within 60 ft speaks, casts a spell with a verbal component, or rolls a natural 1, the Broadcast Demon gains advantage on his next attack roll, saving throw, or ability check before the end of his next turn.

Phase 2 Traits. 

Demonic Broadcast Form. When the Broadcast Demon is reduced to 50% of its maximum hit points, it transforms into its full demon form. It gains +2 AC, 50 temporary HP, and enhanced attacks. All legendary actions increase by 1, and its aura and abilities are amplified as described above.

Always On Air:  now affects creatures within 120 ft

Broadcast Authority: All charmed creatures act as if under a “mass suggestion” (moves, attacks, or follows commands)

Audience Participation. now affects creatures within 120 ft

Multiattack. The Sovereign makes two Reality Rending attack and one Shadowed Tendrils attack

Reality Rending Strike. Melee Weapon Attack: +15 to hit, reach 10 ft., one target.
Hit: 24 (5d8 + 8) psychic damage. The target must succeed on a DC 23 Wisdom saving throw  or be stunned until the end of its next turn.

Shadowed Tendrils. Melee Spell Attack: +15 to hit, reach 20 ft., one target.
Hit: 18 (4d6 + 8) necrotic damage, and the target must make a DC 23 Strength saving throw or be restrained until the end of its next turn as shadowy tendrils coil around them.

While restrained by this attack, the target takes 7 (2d6) necrotic damage at the start of each of its turns until they escape (Strength or Acrobatics DC 23).

Phase 2 Actions

 Shadowed Tendrils (Enhanced): Deals a additional 1d6 and can now target up to 3 creatures within 20 ft at once, and restrain them (DC 23 Strength or escape).

Reality Rending Strike (Enhanced): All creatures within 10 ft of target must succeed on a DC 23 Wisdom save or take half damage and be stunned until the end of their next turn.

The Broadcast Demon can take 3 legendary actions (4 in demonic form) choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. The Broadcast Demon regains spent legendary actions at the start of its turn.

Polite Interruption. (1 action) The Broadcast Demon interrupts a creature’s action. Target must succeed on a DC 23 charisma saving throw  orlose their reaction and bonus action this turn.

Shadowed Reach. (2 actions) The Broadcast Demon lashes out with shadowy tendrils Melee Attack: +15 to hit, reach 20 ft., one target.Hit: 14 (4d6) necrotic damage, and the target is grappled (escape DC 23 Strength).

Encore. (3 Actions)  The Broadcast Demon repeats one creature’s last action as if it were his own. Target a creature within 60 ft. that just made an attack or cast a spell. That action is mirrored: the Demon makes the same attack or forces the same ability to take effect against a creature of his choice (Dex/Wis save DC 23 to avoid if applicable)