Naruto Shippuden Manga 686 [Those Who Remain and Those Who Pass

Hagoromo's spirit informs the Hokage of the events that transpired after the Infinite Tsukuyomi was cast. He also informs them that due to Madara's lower half still containing Yang-Kurama's as well as both Indra's and Asura's chakras, they fully combined, resulting in his spirit finally emerging. Minato questions Hagoromo on a technique he told them earlier, but he said it would require a huge amount of chakra, which he does not have at the moment, having given Naruto and Sasuke his chakra earlier.