Balzahor, Swarmer of the souls

Dark Permeability:
Balzahor would have the ability to blend into any dark area becoming unperceived, all attack rolls have a disadvantage against him while he's unperceived.

Balzahor's Call:
 Balzahor would call your name, roll a Wisdom Saving Throw, if you fail you are charmed, as he stares into your soul stealing it, your soul is turned into one of the flames on his candle sticks, you still control your body but you don't have your soul, he can have 3 at a time, and when he has all 3 he gets to activate his Ultimate "Ascended Soul".

Blast of the Ruined Soul:
 Balzahor would aim his candle at you before unleashing a cone of blue magic dealing 11d10 of All Damage roll a Dexterity Saving Throw to take half damage.

Ascended Soul:
After collecting all 3 souls he would activate Ascended Soul, he would blow out all 3 candles, a Blue Smoke rose from the blown out candle sticks, the smoke would collect together turning into a Solid Gem that grants the holder the ability to control all 3 souls that he collected, all 3 souls are returned after the gem is destroyed.

Rising Shadows:
 Shadow hands would rise from the ground grabbing your leg pulling you into the earth, it takes 3 turns to pull you in, roll a Strength saving throw every round to attempt to escape, he can summon up to 2 every round, you can attack but you cannot move from your spot while the hands grab onto you, this attack is unavoidable unless you have natural perception 24+, if you do then roll a Dexterity Saving Throw.

Call to Service:
 He would have the ability to summon in some of the people he has trapped in his lair out to fight for him in undead form, on their death, they are freed out his lair instead of killed, roll insight 25+ to figure this out.