Genjutsu Immunity

Genjutsu Immunity is a gigantic advantage that everyone who surpasses beyond the ultimate precipice of Genjutsu Power, which allows them to basically Chakra Coat their Psyche; due to this, Genjutsu will never be able to work on them. Once the ultimate Grandmastery of Genjutsu has been achieved, which is almost unheard of to begin with, nobody can fight them using Genjutsu, and it's almost impossible to counter their own Genjutsu techniques.