Mind Flayer

Medium aberration, lawful evil
Armor Class 15 (breastplate)
Hit Points 71 (13d8 + 13)
Speed 30 ft.
STR
11 (+0)
DEX
12 (+1)
CON
12 (+1)
INT
19 (+4)
WIS
17 (+3)
CHA
17 (+3)
Saving Throws Int +7, Wis +6, Cha +6
Skills Arcana +7, Deception +6, Insight +6, Perception +6, Persuasion +6, Stealth +4
Senses darkvision 120 ft., passive Perception 16
Languages Deep Speech, Undercommon, telepathy 120 ft.
Challenge 7 (2900 XP)

Magic Resistance. The mind flayer has advantage on saving throws against spells and other magical effects.

Innate Spellcasting (Psionics). The mind flayer's innate spellcasting ability is Intelligence (spell save DC 15). It can innately cast the following spells, requiring no components:

At will: detect thoughts, levitate
1/day each: dominate monster, plane shift (self only)
ACTIONS

Tentacles. Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. 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 15 Intelligence saving throw or be stunned until this grapple ends.

Extract Brain. Melee Weapon Attack: +7 to hit, reach 5 ft., one incapacitated humanoid grappled by the mind flayer. Hit: The target takes 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 magically emits psychic energy in a 60-foot cone. Each creature in that area must succeed on a DC 15 Intelligence saving throw or take 22 (4d8 + 4) 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.

Psionic tyrants, slavers, and interdimensional voyagers, mind flayers are insidious masterminds that harvest entire races for their own twisted ends.
Monster Manual
Mind Flayer