Captain N'ghathrod

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, silvery barbs 

1/day each: dominate person, plane shift (self only)

Multi attack: You may make two attacks with mind razor and take the mind blast action or cast a spell.

Mind Razor  Melee Weapon Attack: +7 to hit, reach 5 ft., one creature. Hit: 20 [rollable](1d6+2d4+ 4); On a hit

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.

Cunning action:  May take a hide, dash, or disengage action as a bonus action.

Brain sense:  The mindflayer can sense the intelligence scores and the spell casting abilities of creatures within 100 feet of them for one minute..

Parry. The knight adds 2 to its AC against one melee attack that would hit it. To do so, the knight must see the attacker and be wielding a melee weapon.