Madara is currently forcing Obito to activate Rinne Tensei. The battlefield, especially Minato and Naruto all have their attention on Obito as Madara's will takes over Obito via his white Zetsu half.
Remember when madara put his will in a zetsu and turned it half black. It's something like that. His will is over powering Obito to bring madara back to life
Apparantly Madara stored some mini black rods into Obito's zetsu half as insurance. By pouring his chakra into the rods, Madara was able to control Obito.
The black coloring on Obito's body is a part of Madara. He will control Obito and make him use the Rinne Tensei, which will revive Madara into a living body.
With a living body, Madara can then become the Juubi host.
Because Madara was reincarnated and not revived, he needs Obito to perform the Samsara of Heavenly Life Technique so that he can become the Ten-Tails' jinchūriki. Obito has noted that this would result in his own death.
Madara is currently forcing Obito to activate Rinne Tensei. The battlefield, especially Minato and Naruto all have their attention on Obito as Madara's will takes over Obito via his white Zetsu half.