Your Intelligence score increases by 2, and your Charisma score increases by 1

Failed Illithids mature at the same rate as humans, and have an average lifespan of 125 years.

Failed Illithid tend toward Lawful alignments as a result of the strong hierarchy of normal Illithid society, while normal mind flayers are usually evil aligned, with the negative, sometimes torturous treatment Failed Illithids receive from their Illithid brethren, they generally turn to a lawful neutral alignment. 

On average Failed Illithids are slightly shorter than normal mind flayers, being usually between 5 and 6 ft tall.

Your base walking speed is 30ft

As a Failed Illithid, you can speak, read, and write Common and Deep Speech, and you can read and write Qualith

accustomed to the underdark, but not fully formed, Failed Illithids have darkvision up to 60 ft.

You gain proficiency in the Arcana skill and resistance to Psychic damage

Melee Weapon Attack Int + prof. to hit. 1d6 psychic damage. At level 5, on hit you can use a bonus action to attempt to grapple the target.

at lvl 10, Melee weapon attack INT + Prof. to hit, 1d10 + int psychic damage on hit. target one humanoid that is grappled by you. If this attack reduces a target to 0 hit points the failed Illithid kills the target and extracts its brain.