You gain the following features.

Tentacle Arm. You make an unarmed attack roll using your Dexterity Modifier for attack and damage rolls. You gain a +2 bonus to attack and damage rolls made with this magical unarmed attack, but attack rolls made against aberrations with this weapon have disadvantage. A creature hit by this weapon takes 2d6 psychic damage. When you roll a 20 on the d20 for an attack roll with this weapon, the target is stunned until the end of its next turn. You are proficient with this attack.

Disintegration Eye (Recharge 6). Dexterity Saving Throw: DC 16. Failure: 36 (8d8) Force damage. If the target is a nonmagical object or a creation of magical force, a 10- foot Cube of it disintegrates into dust. Success: Half damage. Failure or Success: If the target is a creature and this damage reduces it to 0 Hit Points, it disintegrates into dust.

Tongue of Madness (Recharge 6). When you take the Attack action on your turn, you can replace one of your attacks with a scream of magical energy in a 15-foot cone. Each creature in that area must make a Dexterity saving throw (DC = 8 + your Constitution modifier + your proficiency bonus). On a failed save, the creature takes 4d10 psychic damage. On a successful save, it takes half as much damage.

You gain the ability to speak telepathically up to 90ft.