Using Kurama's chakra, Naruto and Sasuke continually reshaped the power they needed. Although both had been powerful before, their greed for too many abilities had made their progress painfully slow and left their strength unfocused. This time, they intended to fully fuse their abilities and discard whatever they did not need.
The Rinnegan in Naruto's right eye slowly faded and regressed, changing from a Rinnegan into a Mangekyō Sharingan, then from a Mangekyō Sharingan into a three-tomoe Rinnegan, then two-tomoe, then one-tomoe, until it finally became an ordinary blue eye. Immediately afterward, it became a White Eye. Meanwhile, the White Eye in his left eye kept changing, turning gold, then becoming a blue Tenseigan, before finally reverting to its original White Eye form. Yet this White Eye now gave off a terrifying feeling. The instant it reverted, Naruto's aura surged wildly, startling even Killer B, who stood nearby guarding the pair.
Sasuke underwent an equally earth-shattering transformation. His right eye spun rapidly, and the four tomoe on its Rinnegan slowly multiplied until there were eight. It then became a Mangekyō Sharingan, its eight-pointed star pattern reappearing before a tomoe emerged at each point of the star.
The original four tomoe in his left eye also vanished, and six tomoe slowly appeared in their place. The moment those six tomoe emerged, Sasuke's aura soared as well. Their combined auras shook all of Konoha, startling many of the genin who had stayed behind into thinking there was an earthquake.
Only those guarding the area knew what had happened. The powerful auras shattered the barrier they had erected, and the guards hurried to repair and reinforce it. Only then did they barely manage to hold it together.
"Eight-Tails, these two are unbelievably strong," Killer B said in shock. "They look a lot stronger