Kaguya's mega sharinnegan literally pulled people into different dimensions, but then again Obito had a very similar dimensional ability, leading me to believe they are connected. Tsukyomi is basically creating an artificial illusion dimension for the mind. When the King of Hell was summoned in the manga, he had amateresu flames around him, leading me to believe perhaps Amaterasu is literally summoning the flames of hell into the mortal world. Susanoos often reflect the characteristics of the caster, for example Kakashi's susanoo had his scar on one eye symbolized by a slash. Perhaps Susanoo is bridging a gap into an alternate spirit world where your spirit avatar exists and summoning it forth in the form of an armored titan?

