Board Thread:Theories and Speculation/@comment-33256714-20171005000302/@comment-734582-20171007132656

Indk21 wrote: So why is necessary to unlock both Mangenkyou abilities to achieve Susanoo as third ability of the Mangenkyou? After Sasuke used Susanoo against Danzo, he felt like every cell in his body hurt. Apparently, Susanoo needs to be stabilized before it can truly be used without eyes. Tayuya once used spirits that drained physical energy, as if they took what they lacked. So, i'd say the same is true for the Susanoo: in order to be stable, it needs to be fed the user's physical energy until such moment that it is complete.

In other words, Susanoo first needs to be cast somehow before it can be used independently.

Vladosaurus wrote: Itachi's words: "You need to unlock both tsukuyomi and amaterasu to use the Susanoo" are clearly false. I think he simply meant that you need both eyes to use Susanoo. Obito wasn't able to use it until he had his second eye back, and only then in death could he use it. Indk21 wrote: Kishimoto's breaking logic of his own work universe, like he did many times in final arc. I think stuff like the Susanoo and the Rinnegan work like intended, he just never got around to introducing it properly. In the case of Gaiden, i think it was intended to show the true nature of Sasuke's eye, just as Madara's use of Susanoo was meant to show it's true nature. Sometimes Kishimoto has characters show the true intent of certain jutsu or abilities, like how Kaguya showed the true intent of Shikotsumyaku/Kamui or how Minato showed the true intent of the Rasengan.