Board Thread:Versus Debates/@comment-26636534-20170822151908/@comment-5085906-20170826124117

Ravenlot 27 wrote: Anyway, during the clash with Fuu, it didn't seem that the latter tried to use Shintenshin and failed, rather that Fuu only made the hand sign, but didn't have enough time to initiate the technique.

Regarding Kamui, well, if his mind can perceive both the real and Kamui dimension evenly, it means that mind-affecting techniques should still be effective on him even in intangible state. At the same time, Izanami needs some physical requirements (the setting of "A" "B" "C" events to create a basis for a loop), while it would be hard to met this conditions if Obito doesn't have a physical body. He said "Shintenshin no Jutsu!" signalling the technique's activation, but held back when he saw Obito quicksand-ing into the ground. But yeah you're right - whether or not Obito is impervious to genjutsu in his intangible state is debatable and also not relevant, considering Itachi obviously needs to fill some criteria to do the jutsu, otherwise he would have triggered it in the beginning.

It's still possible that he can activate it if Obito so much as touches him, though, making him re-live that touch. Not saying MS Obito wouldn't eventually win, but it would be a much closer fight than Rinnegan Obito v. Itachi.