The Illithid's guest

Upon sleeping or otherwise losing consciousness, make a wisdom save against your spell save dc. If you fail your save, you spend the time unconscious connected to the Illithid hive-mind. Upon waking, make another wisdom save with your standard wisdom save score: a failed save results in a minus 3 to INT and WIS scores that last until the next time you fall unconscious, a successful save results in a plus 6 to INT and WIS scores until the next time you fall unconscious. Each consecutive failure of the wake up save adds plus 2 to the save and score loss until the afflicted's int or wisdom reaches 0, at which point they become a thrall of the mindflayers.