Captives whose brains have been removed and devoured by mind flayers are often used as hosts. The mind flayers surgically implant a larval parasite into the skull cavity. The mind flayer can now command the thrall, and experience the world through its sense organs. Instinct: to execute the orders of its master

• Advance robotically
• Infiltrate another faction and gather intel
• Allow the master to see through its eyes
• Telepathically alert the master of danger