Astrius, God of Chaos and the Unknown

Discorporation. When Astrius drops to 0 hit points or dies, his body is destroyed, but his essence travels back to the Unknown Realm and is unable to take physical form for a time.

God of Chaos. Whenever a creature becomes within 30ft of Astrius, they must succeed a DC 22 Wisdom saving throw or become engulfed in madness. If they succeed, they are immune to this effect for one day.

Legendary Resistance (3/Day). If Astrius fails a Saving Throw, he can choose to succeed instead.

Limited Magic Immunity. Unless he wishes to be affected, Astrius is immune to spells of 6th level or lower. He has advantage on saving throws against all other spells and magical effects.

Regeneration. Astrius regains 30 Hit Points at the start of his turn.

Innate Spellcasting. Astrius can innately cast prismatic spray,feeblemind(1/Day),dream,modify memory(3/day)crown of madness,darkness, (at will)

Spellcasting. Astrius is a 20th-level spellcaster. Its spellcasting ability is Wisdom(spell save DC 24, +19 to hit with spell attacks). Astrius has following spells prepared:

Cantrips (at will): eldritch blast, gust, ray of frost, vicious mockery

1st level (4 slots): bane,chaos bolt, chromatic orb,hex,hideous laughter,magic missile, witch bolt

2nd level (3 slots): acid arrow,alter self,hold person, ray of enfeeblement,scorching ray

3rd level (3 slots): counterspell,catnap,blink,lightning bolt,nondetection,wind wall

4th level (3 slots): charm monster, confusion,polymorph,phantasmal killer,greater invisibility,hallucinatory terrain

5th level (3 slots): dominate person,dream,modify memory,hold monster,geas

6th level (2 slots): disintegrate,eyebite,forbiddance,programmed illusion

7th level (2 slots): divine word, reverse gravity,power word pain,prismatic spray

8th level (1 slots): reality break, feeblemind, maddening darkness

9th level (1 slots): ravenous void, psychic scream

Change Shape (4/Day). Astrius magically polymorphs into a humanoid or beast that has a challenge rating equal to or less than his own, or back into his true form. When Astrius drops to 0 hit points or dies, his body is destroyed, but his essence travels back to the Unknown Realm, and he is unable to take physical form for a time. Any equipment he is wearing or carrying is absorbed or borne by the new form (Astrius's choice). In a new form, Astrius retains his Ability Scores, Alignment, Hit Points, Hit Dice, Innate Spellcasting, Legendary Resistance, Limited Magical Immunity, ability to speak, Senses, Proficiencies, as well as this Action, but his AC, movement modes, and other Actions and Legendary Actions are replaced by those of the new form, and Astrius gains any statistics and capabilities (except Class Features, Legendary Actions, and Lair Actions) that the new form has but that Astrius lacks.

Multiattack. Astrius can use his Mad God's Gaze. He then makes three tendril attacks.

Mad God's Gaze. As an action, Astrius may stare directly into the soul of a creature, forcing false thoughts into their head, breaking their mind. The creature must make a DC 20 Wisdom saving throw or take 6d8 psychic damage, half on a successful save, and they get -10 to their next skill check or saving throw.

Eldritch Tendrils. Melee Weapon Attack: +19 to hit, reach 25 ft., 1 target. Hit: 26 (4d8 + 10) piercing damage and 6d4 psychic damage. 

Move. Astrius may move up to half is walking or flying speed

Lash. Astrius may make an attack with his Eldritch Tendrils.

Gaze. Astrius may use his Mad God's Gaze action.

Cantrip. Astrius may cast a cantrip.

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