Often distinguished by a metal hood that rises from the backplate of their [[Power Armour]], it uses a set of interwoven intricately aligned crystals to nullify an opponents psychic attacks;{{Fn|1}}{{Fn|3}} however they are of a very arcane design and are likely not to have been produced perfectly and so are not one hundred percent effective. This was demonstrated when various Space Marine Librarians turned to [[Chaos]] during the [[Horus Heresy]], becoming [[Chaos Sorcerer]]s. Psychic hoods are also occasionally employed by [[Inquisitors]].{{Cite This}}