Are the tailed beasts immortal?

[Guntah]

Hachibi was still hachibi. Naruto used kyuubi's chakra not the kyuubi transformation. Sasuke used enton not amaterasu.

No difference, I don't see why the Kyuubi couldn't do the same, no difference.

Alternatively, we have this.

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, and its shown a couple more times in the series. Reference back to Kurama repelling Naruto's very oversized Rasengan and, yes, Naruto blasting back Sasuke's flames with it during their first Valley of the End conflict. I think you know where I'm going with this.