Increase your Intelligence score by 2 and your Wisdom score by 1.

Illithid reach adulthood in their late teens and live a little over a century.

The Illithid are lawful evil, looking to expand their dominion over all other creatures, controlling their minds to use them as hopeless slaves and devouring their brains for sustenance

Illithids vary widely in height and build, from barely 5 feet to well over 6 feet tall. Regardless of your position in that range, your size is Medium.

Your base walking speed is 30 feet.

You can speak, read, and write Common and Deep Speech.

At 1st level you know the message cantrip.

When you reach 3rd level, you can cast the detect thoughts spell once with this trait, and you regain the ability to do so when you finish a short rest.

When you reach 5th level, you can cast the levitate spell once with this trait, and you regain the ability to do so when you finish a long rest.

Intelligence is your spellcasting ability for these spells. When you cast them with this trait, they don’t require components.

The mind flayer magically emits psychic energy in a 15-foot cone. Each creature in that area must make a Intelligence Saving Throw. The DC for this saving throw equals 8 + your Intelligence modifier + your proficiency bonus. A creature takes 2d6 psychic damage on a failed save, and half as much damage on a successful one.

The damage increases to 3d6 at 6th level, 4d6 at 11th level, and 5d6 at 16th level. After you use your breath weapon, you can’t use it again until you complete a short or long rest.

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