The third Dojutsu is a unique form of Dojutsu constructed upon the foundation of hypnosis—the most core and inscrutable power of the Sharingan.
In essence, this Dojutsu is a spiritual space forged from pupillary power. For the Uchiha Clan, a more precise term would be a pupillary space.
Like an invisible fortress hidden deep within the eyes, it can continuously absorb and converge pupillary power, thereby massively amplifying the potency of Genjutsu. Especially when combined with the Sharingan's innate Genjutsu, the resulting effects reach the absolute pinnacle.
Chapter 451