Balasar "Ego"

[FORM] Storm Dragon. Ego is able to sacrifice his vitality to embody the Storm itself. Ego can use a bonus action to take 4d6 necrotic damage that can't be reduced in any way to call forth a lighting storm on its location or within a 30ft. radius. 
Change to the appropiate Statblock

Fast Regeneration. Ego regains 3 hit points (Con Modifier) at the start of his turn. If Ego takes radiant damage, this trait doesn't function at the start of Ego's next turn. Ego is able to take short rests in 10 minutes. 2 hours for a long rest

Tail. Ego can use its tail to activate magic items, grab, push or hold something.

Bound to the Abyss. Ego has an abyssal demiplane in his body. He can swallow things and store them inside this plane.
The number of Creatures Ego can store in this demiplane is equal to his Proficiency Bonus (4)
The number of Demons Ego can store in this demiplane is equal to his CHA modifier (3)

Eye of Dethram. Ego has advantage on Wisdom (Insight) and Intelligence (Investigation) checks.
As a bonus action can Ego open the eye lid on his body and see through the Eye of Dethram within for 1 minute. While the Eye is open, Ego gains Truesight with a range of 60 feet.

Keen Hearing. Ego has advantage on Wisdom (Perception) checks that rely on hearing.

Elven boots. Ego has advantage on Dexterity (Stealth) checks.

Fiendish Resistance. Ego has advantage on saving throws against spell/magical effects and being charmed or frightened.

Adaptive Instinct. The Body of Ego adapts to the last damage type taken . When Ego takes damage by an available damage type, he gains resistance against this damage type or has his already innate resistance or immnunity against that damage type strengthend. (available damage types: bludgeoning, piercing, slashing, lightning)
Resistance -> Immunity -> Absorption

Enhanced Body. All physical attacks are made with a +1 on attack rolls and damage rolls, also bludgeoning damage deals double damage to objects and structures.

Reckless. When attacking an enemy, Ego can lower his attack rolls (to a minimum of 0) and add the subtracted number times 2 to his damage rolls.

Innate Spellcasting. Ego's innate spellcasting ability is Wisdom (spell save DC 16, +8 to hit with spell attacks). He can innately cast the following spells, requiring no material components:

At Will: Alter Self (Sizes: Small - Large), Produce Flame (2d8 Fire Damage), Burning Hands (Fire Lightning Damage)

3/day each: Tasha's Hideous Laughter, Magnify Gravity, Inflict Wounds

1/day each: Hold Person, Suggestion, Crown of Madness, Wither and Bloom, Enlarge/Reduce, 

Multiattack. Ego makes two Slam attacks.

Slam. Melee Weapon Attack: +9 to hit, reach 5 ft., 1 target. Hit: 12 (2d6 + 5) [bludgeoning/piercing/slashing] damage.

Lightning. Ranged Spell Attack: +8 to hit, reach 30 ft., 1 target. Hit: 16 (3d10) [lightning] damage.

Summon Demon (1/Long Rest). 

Tail. Melee Weapon Attack: +9 to hit, reach 10 ft., 1 target. Hit: 10 (1d8 + 5) [bludgeoning/piercing/slashing] damage and if the target is Medium or smaller it is grappled(escape DC 16).