Here Obito wasn't even looking at Guy but still phased through his kick.
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Now about Obito being hit by Minato's rasengan, the way i see it is that, Obito has to forcefully stay in the real world when he is about to absorb/wrap someone.
This is why Minato said that timing is crucial, Obito's weakness lies only in the moment of attack, when he forcefully stays in real world and doesn't let his body phase out on contact.
I think although Obito not seeing Guy, but he still can sense his present and also Kakashi is attacking him, the best way to avoide from getting hit by them is activating Kamui Phasing on that time before all the hits is lending on Obito body.
But in the case of Limbo, how Obito will know from where the limbo will attack and when? Unless he is having Rikudou chakra or Rinnegan
Here Obito wasn't even looking at Guy but still phased through his kick.
You must be registered for see images
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Now about Obito being hit by Minato's rasengan, the way i see it is that, Obito has to forcefully stay in the real world when he is about to absorb/wrap someone.
This is why Minato said that timing is crucial, Obito's weakness lies only in the moment of attack, when he forcefully stays in real world and doesn't let his body phase out on contact.