"Crumbling" (崩落, Hōraku) is chapter 413 of the original Naruto manga.
Killer B develops a chakra shroud that he attacks Taka with. Although they are able to dodge, Sasuke realises that they will not be able to do so indefinitely. He uses his Mangekyō Sharingan to catch B in a genjutsu and, believing he has won, lets down his guard. The Eight-Tails releases B from the illusion, so he attacks and fatally injures Sasuke. While Jūgo heals him, B fully transforms into the Eight-Tails.