Ability Score Increase. Your Intelligence score increases by 2, and either your Wisdom or Charisma score increases by 1.

You can use your action to emit a psionic blast in a 15-foot radius around you dealing 2d6 psychic damage. When you use your mind blast, each creature in the area of the blast must make a Intelligence saving throw. The DC for this saving throw equals 8 + your Intelligence modifier + your proficiency bonus. A creature takes 2d6 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 mind blast, you can’t use it again until you complete a short or long rest.

Your innate psionic ability. At 5th level you can cast Detect thoughts at will. Starting at 8th level, you can also cast levitate on yourself at will. Once at 11th level, you can cast plane shift once a day, targeting yourself only, and at 15th level you can cast dominate monster once a day. Intelligence is your spellcasting ability for these spells.

You can speak, read, and write Deep Speech, Undercommon and can read and write in Qualith, the Illithid way of writing that can only be read through touch with your tentacles.

Illithids are born in darkness and live in the darkest corners of the world; you have superior vision in dark and dim conditions. You can see in dim light within 120 feet of you as if it were bright light.

While a creature that has a brain is restrained, Incapacitated, or Grappled by you, you can use your Action to surround its head with your tentacles and cause 2d10 damage to it. When its health is 0, you may use another action to devour its brain. When you do, you can learn one piece of information that the creature knew. Roll an Investigation check, and on a success, you learn what you want to know if the creature knows it. You also gain 1d4 hit points providing the creature had an intelligence of 5 or higher.

You can communicate mentally with another creature that knows at least one language within a 60-foot radius. This creature doesn't need to share a language with you but unless they have telepathy themselves they can only receive and respond but can't initiate or terminate a telepathic conversation. You must be conscious to use this trait and cannot telepathically communicate with multiple creatures at once.

An Illithids innate connection to the eldritch realm, grants supernatural bonuses to Eldritch blast. The damage increases by 1d10 and the range extends by 60ft.

Illithids normally have a natural tendency towards hierarchy, discipline, and cruelty, and have an alignment of lawful evil. Some individuals find themselves developing more-individualistic personalities than their fellows early after ceremorphosis and have an alignment of neutral evil. A minority lack the characteristic sadism of their brethren while retaining their preoccupation with the organization, and have an alignment of lawful neutral. Any illithid of any other alignment, usually the product of unusual circumstances such as mutation, magical alteration, extensive contact with unshackled non-illithid minds while cut off from the networked communal intelligence of their colonies, or intervention by otherworldly forces, is likely regarded by others of its kind as either a disgusting social deviant and pariah, or, at worst, as pollution to be purged. Many such illithid are either mentally wiped blank and re-educated or simply thrown out of their home communities if their natures are too open and offensive to their fellows' sensibilities.