Mind blast

The mind blast was a psionic ability possessed by mind flayers, ulitharids, and elder brains to neutralize the cognitive abilities and psionic powers of other creatures. Although most frequently used as an offensive ability, mind flayers used low-energy versions of mind blasts to slowly erode their victims' personality in order to produce more docile thralls.

Effect
A typical mind blast affected all sentient creatures within a 60-foot (18-meter) cone emanating from the mind flayer. Anyone unable to resist suffered damage and was rendered stunned and unable to act for one minute. Mind flayers could also use a version of mind blast specifically designed to drain the psionic powers of a single target.

A low-power version of mind blast could be applied to a victim over a period of 24 hours. The effect was the complete destruction of the victim's personality, leaving only a partially empty shell behind that could be easily trained into a perfectly docile thrall to serve the illithid colony's purpose. Once their minds were completely dissolved, the thralls became immune to the effects of the mind blast so, in case of a large-scale fight, the mind flayers did not need to worry about hitting their own troops.

History
Mind flayers typically used mind blasts to hunt, dragging off their stunned victims in order to feed on their brains.