Mangekyō

The is technique passed down through the Kurama Clan.

Overview
The Mangekyō is a powerful illusion-based technique utilized by members of the Kurama Clan for the specific purpose of defending themselves against Genjutsu. After sensing out and confirming that a Genjutsu is being used, users are able to "latch on" to the technique and analyze it. Unlike other techniques which simply decrypts and "reflects" the technique back on to the caster, the Mangekyō instead scans whatever Genjutsu is being used and encrypts a special virus into it. This virus then spreads through the technique, giving the caster of the virus control over the illusion and allowing them to forcibly shut it down: completely destroying the technique.

A second aspect of the technique also exist: when used by more skilled and experienced members of the Kurama Clan, users are able to completely take over the original illusion and bring out its fullest potential. As if they'd cast the technique themselves, users are able to "drag" the original caster into the taken over illusion. While this act alone causes an incredibly high amount of mental damage as a result of the confusion and stress of having their illusion taken over, when combined with Chomūmyaku, members of the Kurama Clan are also able to deal to physical damage from within the illusion through psychosomatics, which is capable of even killing their opponents.