Avatar of The Ancient Dark

Discorporation. When Avatar of The Ancient Dark drops to 0 hit points or dies, it's body is destroyed but it's essence travels back to it's domain in the Shadowfell, and it is unable to take physical form for a time.

Innate Spellcasting- (Spell save DC 21) It's spellcasting ability is Intelligence.

Cantrips (at will): Toll The Dead, Eldritch Blast, Mage Hand, Prestidigitation, Chill Touch (4d8)

1st level (4 slots): Detect Magic, Shield of Faith, Shield, Magic Missle

2nd level (3 slots): Detect Thoughts, Mirror Image, Misty Step

3rd level (3 slots): Counterspell, Blink, Lightning Bolt, Spirit Guardians

4th level (3 slots): Banishment, Dimension Door, Stoneskin

5th level (3 slots): Cone of Cold, Destructive Wave, Negative Energy Flood

6th level (2 slots): Conjure Fey, Harm, Circle of Death

7th level (1 slot): Finger of Death

8th level (1 slot): Mind Blank

*The Avatar of The Ancient Dark casts Shield, Spirit Guardians, and Mind Blank spells on itself before combat.

Legendary Resistances (3/Day)- If Avatar of The Ancient Dark fails a saving throw, it can choose to succeed instead.

Limited Magic Immunity- Unless it wishes to be affected, Avatar of The Ancient Dark is immune to spells of 3rd level or lower. It has advantage on saving throws against all other spells and magical effects.

Magic Weapons- Avatar of The Ancient Dark weapon attacks are magical.

Regeneration.  Avatar of The Ancient Dark regains 30 hit points at the start of his turn.

Multiattack- Avatar of The Ancient Dark can use it's frightful presence. It then makes three attacks one with it's tentacles, and two with it's claws.

Frightful Presence- Each creature of Avatar of The Ancient Dark’s choice that is within 60 feet of Avatar of The Ancient Dark and aware of it must succeed on a DC 19 Wisdom saving throw or become 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 Asmodeus's Frightful Presence for the next 24 hours.

Tentacle Grab- Melee Weapon Attack: +12 to hit, reach 15 ft.,  Hit: 18 (1d10 +12) [Necrotic] damage. Target must make a DC 20 Strength Saving Throw or become grappled. If target fails twice, they then become Restrained.

Claw Swipe- Melee Weapon Attack: +12 to hit, reach 15 ft.,  Hit: 24 (2d10 +12) [Necrotic] damage. 

Shadow Needles. Ranged Weapon Attack: +12 to hit, range 60/120 ft., one target. Hit: 28 (4d6 + 12) necrotic damage.

Incorporeal Movement- Moving through the Aether between the planes, Avatar of The Ancient Dark, When attacked, can use it's reaction to cast Misty Step. This does not consume a spell slot. Anyone grasped by it's tentacles move with it.

Avatar of The Ancient Dark 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. Avatar of The Ancient Dark regains spent legendary actions at the start of his turn

Incorporeal Movement (Costs 2 Actions). Moving through the Aether between the planes, Avatar of The Ancient Dark can use 2 Legendary Actions to cast Misty Step. This does not consume a spell slot. Anyone grasped by it's tentacles move with it.

Fellweave Burst (Costs 2 Actions)- Avatar of The Ancient Dark can cast a spell of 3rd level or less.

Tentacle Slam (Costs 1 Action)- If Avatar of the Ancient Dark has someone grappled or restrained, it may use a Legendary Action to slam them into the ground for 4d6 [Bludgeoning] damage.

One with the Darkness (Costs 3 Actions)- If a target in the grasp of Avatar of the Ancient Dark's tentacles becomes Incapacitated or Unconscious, they are dragged into and extra-dimensional space within The Avatar of the Ancient Dark. While in this space, they cannot be the target of any spells, abilities, or effects. They are released when Avatar of The Ancient Dark is reduced to zero Hit Points.