A Mind Ward
Mind Demons are briefly mentioned in The Painted Man in the ruins of Anoch Sun, but is officially introduced in The Desert Spear. These demons are extremely powerful and live thousands of years, acting as princelings for the demons and serving the queen. Their power is beyond normal demons since they see wards, their patterns, and their weakness. Mind demons can enter human minds, monitoring and modifying thoughts, leaving their victims unaware they were ever tampered with. However, there are wards that prevent a mind demon from entering the mind. The only known people to have possessed them are Arlen, Kaji and Jardir until the third book in which Leesha Paper starts distributing it, along with a warning to run from the Krasian army, which was preparing to head that way in the form of a translated Krasian song (The Song of Waning), on the way back to Deliverer's Hollow. As seen in The Desert Spear, however, the mind ward does not work when the person is in the between state (dematerialize) .the mind link can be used both ways as when Arlen fought with this demon he could see visions of the core. Each Mind Demon typically has one Mimic Demon permanently linked to itself through thought and is used as a bodyguard and a servant obeying without question.
The Mind Demons themselves had comments about "High Princes" indicating that their may be different breeds of Mind Demons.