Claws

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) slashing damage.

Ego Whip

The intellect devourer targets a creature with a brain within 60 feet. The target makes a DC 13 Intelligence saving throw. On a failure it takes 14 (4d6) psychic damage and is rattled for 1 minute. If it is already rattled by Ego Whip it is also stunned. The target repeats the saving throw at the end of each of its turns ending both effects on a success.

Body Thief

The intellect devourer enters the nose and mouth of an incapacitated humanoid within 5 feet. The target must be Small or larger have a brain and have an Intelligence of 4 or higher. The intellect devourer eats the targets brain and takes control of the target. The intellect devourer leaves the body if the target is reduced to 0 hit points if the target is affected by dispel evil and good or another effect that ends possession or voluntarily as a bonus action. A creature killed by the intellect devourer can be restored to life by resurrection or similar magic.

While the intellect devourer is in control of the target, the intellect devourer retains its own Intelligence, Wisdom, and Charisma, its telepathy, and its knowledge of Deep Speech

It otherwise uses the targets statistics including proficiencies languages class features and spells. It has vague knowledge about the targets life but must make a DC 15 Intelligence check to recall specific facts.