Your Intelligence score increases by 2. Your Wisdom and Charisma scores increase by 1. Your Strength and Constitution scores decrease by 2.

Illithids finish the process of ceremorphosis by age 9, and become fully mature by 15. The maximum lifespan of an Illithid is unknown, though they rarely live past 150 years - and the life of a renegade is far more perilous than usual.

As Illithids under the control of Elder Brains are almost uniformly Lawful Evil, there are many renegades who do not deviate far from that path, but there are no guarantees with one who has been left to make their own choices.

Illithids are usually between 5 and 6 feet tall, and typically weigh from 114 to 270 pounds. Your size is Medium.

Your base walking speed is 30 feet. Your base swimming speed is 20 feet.

With strange, alien eyes and a life spent in both the Underdark and strange, dark planes, the sight of an Illithid is very different from a human's. Similar to the abilities of warlocks, they gain the ability to see in total darkness with no trouble at all, up to a distance of 120 feet. They can see invisible creatures and objects, automatically detect visual illusions and succeed on saving throws against them, and perceive the original form of shapechangers and creatures transformed by magic. In addition, they can see into the Ethereal plane - but these bonuses to their sight only function in normal or magical darkness, not in dim or full light. Full sunlight is the worst for them - unacclimatized to the bright light of the sun, if they are not protected their eyes may be injured when entering full sunlight. Under this condition, they must make a Constitution saving throw (DC 10) to avoid being blinded for one minute and taking 1d4 radiant damage. Regardless of eye protection, or the success or failure of this throw, Illithid renegades take disadvantage on attack rolls and Wisdom checks that rely on sight when they, what they are trying to perceive, or the target of their attack is in full sunlight.

Though sundered from the power of the Elder Brains, renegades retain formidable psionic power. Once you reach 3rd level, you gain access to the Levitate and Detect Thoughts spells. At 13th level, you can cast Plane Shift, targeting only yourself. At 15th level, you can cast Dominate Monster. You can only cast each of these spells once per long rest. Intelligence is your spellcasting ability for these spells, and you do not require material components for them.

Powerful telepaths, Illithids are capable of instantaneous telepathic communication with any creature within 120 feet that understands at least one language. You require a line of sight with the subject, and an unwilling subject may choose to make a Wisdom saving throw (DC equal to your level plus your proficiency bonus) to block out the message.

While speaking telepathically with a creature, you can use an action to grant them the ability to respond telepathically for one hour. You can only give this ability to one creature at a time; if you give it to another creature, it removes the ability from the first. At level 9, you can grant this ability to two creatures at once.

As powerful psychics themselves, Illithids are familiar with the tricks by which minds are attacked, and prepare for them. They have advantage on Intelligence, Wisdom, and Charisma saving throws.

Beginning at level 6, Illithid renegades can use an action to emit a psionic blast in a 25-foot cone in front of them. Each creature in the blast area must make an Intelligence saving throw (DC equal to 8 plus your Intelligence modifier plus your proficiency bonus) or take 3d6 psychic damage and be stunned for one minute, or take half as much damage and avoid the stun on a successful save. Stunned creatures can repeat the saving throw on their turn to end the effect if successful. Damage increases by 1d6 and blast radius increases by 10 feet at 11th level (4d6, 35 feet), and 16th level (5d6, 45 feet). This ability can be used once per long rest.

The four tentacles that adorn an Illithid's face are not merely for decoration. Strong and prehensile, they are often an Illithid's preferred weapon in melee combat. Your tentacles are natural melee weapons, which you can use to make unarmed strikes. If you hit with them, you deal slashing damage equal to 1d4 + your Dexterity modifier, instead of the bludgeoning damage normal for an unarmed strike. You may also use your tentacles to grapple; make a Strength (Athletics) check, contested by the target's Strength (Athletics) or Dexterity (Acrobatics) check. If you succeed, you subject the target to the Grappled condition. The condition specifies the things that end it, and you can end the grapple whenever you like (no action required).

An Illithid's got to eat, and there's really only one thing that hits the spot. Once per day, when you have a humanoid creature grappled, you may make a strength check contested by the target's choice of a strength or dexterity check. If your check succeeds, the target takes 6 piercing damage - if this damage reduces the target to 0 hit points, its brain is extracted and devoured. Upon devouring a brain, you regain hit points equal to the victim's Intelligence modifier, and gain access to a piece of knowledge or a memory (at the DM's discretion) that the target had access to. This attack cannot be used on constructs. If you devour the brain of an Undead, make a Constitution saving throw (DC 15). If you fail the save, take 2d4 poison damage, become disoriented, and learn no new information from the devoured brain. On a success, take half damage and gain information as usual.

Outside of combat, you may feed on the brains of humanoid creatures that have died within the last minute. In doing so, you regain 1 hit point, and gain access to a piece of knowledge or memory that the target had access to. You cannot feed on constructs or the undead outside of combat.

Piercing damage increases to 12 at level 6, 18 at level 12, and 24 at level 18.

When a renegade Illithid enters a Hive Brain's area of influence, they can sense it, and it senses them. As the Elder Brain attempts to assert control, make a Charisma saving throw (DC 15) to resist. If successful, the DM may choose to repeat the contest in an hour,. If you fail, your alignment becomes Lawful Evil, you are considered Charmed, and must obey any order given by the Elder Brain. If the Elder Brain forces you to begin combat against creatures you had been friendly with, you may repeat the saving throw with disadvantage to attempt to break its grasp - otherwise, the effect lasts until you are moved outside of the Elder Brain's sphere of influence, the Elder Brain is killed, or another effect blocks its telepathy.

You can speak, read, and write Common, Undercommon, and Deep Speech. You are proficient in the Mind Flayer written language Qualith.