Cephalokor, Mind Flayer Arcanist of Rexuil

Innate Psionics . The mind flayer’s innate spellcasting ability is Intelligence (spell save DC 17). It can innately cast the following spells, requiring no material components:

(at will): detect thoughts, levitate

(4 slots): dimension door, phantasmal killer

(3 slots): plane shift

Shadow-Reverent Spellcasting. The Mindflayer is a 11th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). The Mindflayer Arcanist of Rexuil has the following Wizard spells prepared:

Cantrips (at will): minor illusion, prestidigitation, toll the dead, shadow blade

1st level (4 slots): mage armor, shield, disguise self, cause fear

2nd level (3 slots): mirror image, misty step, crown of madness

3rd level (3 slots): counterspell, hunger of hadar, dispel magic

4th level (3 slots): greater invisibility, vitriolic sphere

5th level (2 slots): synaptic static, wall of force

6th level (1 slot): mental prison

Multiattack. The Mindflayer Arcanist of Rexuil can make 3 tentacles attacks.

Tentacle Attack. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 15 (2d10 + 4) [psychic] damage. If the target is Medium or smaller, it is grappled (escape DC 15) and must succeed on a DC 17 Intelligence saving throw or be stunned until the grapple ends.

Extract Brain. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 55 (10d10) [piercing] damage. If this damage reduces the target to 0 hit points, the mind flayer kills the target by extracting and devouring its brain.

Mind Blast (Recharge 5–6). The mind flayer emits a psionic wave in a 60-foot cone. Each creature in that area must succeed on a DC 16 Intelligence saving throw or take 27 (5d8 + 5) psychic damage and be stunned 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.

Shadow Step (1/Day). When a creature hits the mind flayer with a melee attack, it can teleport up to 30 feet to an unoccupied space it can see in dim light or darkness. Until the start of its next turn, the mind flayer has advantage on Dexterity saving throws, and the triggering attacker has disadvantage on opportunity attacks against it.

Cephalokor, Mind Flayer Arcanist of Rexuil can take 2 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. The arcanist regains spent legendary actions at the start of its turn.

Shadow Step. The arcanist teleports up to 30 feet to an unoccupied space in dim light or darkness.

Psionic Lash. The arcanist targets one creature it can see within 60 feet. That creature must make a DC 16 Intelligence saving throw or take 9 (2d8) psychic damage and have disadvantage on its next attack roll before the end of its next turn.

Call of the Veil (Costs 2 Actions). The arcanist opens a rift to the Shadowfell, exuding cold darkness. Each creature of its choice within 20 feet must succeed on a DC 16 Wisdom saving throw or become frightened until the end of its next turn.