Consciousness absorber

A consciousness absorber (AUDIO: The Web of Time) was a device capable of draining a person's mind of their knowledge and experience, leaving them as helpless as a newborn. (TV: The Web of Fear)

The Great Intelligence built an pyramidal, elementary consciousness absorber using plastic components to drain the Second Doctor's mind during the London Event, but encountered River Song and attempted to use it on her before she destroyed it. (AUDIO: The Web of Time)

The Intelligence later constructed a second pyramid and attempted to drain the Doctor's mind and add it to his own, but the Doctor was able to reverse this, attempting to drain the Intelligence before Jamie McCrimmon unwittingly used a Robot Yeti to smash the machine. (TV: The Web of Fear) As such, the Intelligence was left blind and bound to Earth by its locuses. (PROSE: Downtime)