In the current Shinobi World, those who represented the pinnacle of combat power were no longer Uchiha Madara and the First.
The ones who truly stood at the peak of the Shinobi World were shinobi on the level of Uchiha Yue, the Death God, the Sage of Six Paths, and Kaguya Otsutsuki.
Back when they were at the level of the First and Uchiha Madara, if two powerful experts joined forces against a single enemy, they did not need any verbal communication at all. Perhaps a single glance was enough for experts of that level to achieve such tacit understanding. Since even experts like Uchiha Madara and the First could possess such coordination, then Black Zetsu and the Death God's avatar before Uchiha Yue—respectively the representatives of the Death God and Kaguya Otsutsuki—needed no communication whatsoever to attain that same understanding.
Thus, almost the instant Uchiha Yue transformed the First's mental space into a world of Six Paths Samsara...
Rumble!
The First's mental space began to collapse as the world of Six Paths Samsara swept in.
Just as the entire world was about to bury the Death God's avatar and Black Zetsu together, Black Zetsu merely stared fixedly at Uchiha Yue. Then, his body completely turned into darkness and gradually seeped into the First's mental space, intending to use this method to resist the encroachment of Uchiha Yue's Six Paths Samsara!
At the same time!
As Black Zetsu began resisting the invasion of Six Paths Samsara, the Death God's avatar directly arrived at Uchiha Yue's side. Facing Uchiha Yue, who was displaying his power, he completely turned his body intangible, intending to invade Uchiha Yue's body.
Clearly, the division of labor between the Death God's avatar and Black Zetsu was very precise.
One resisted Uchiha Yue's attack, while the other