Tailed Beast Rasengan

To get around the fact he couldn't use either the Tailed Beast Ball or Shadow Clone Technique while in Nine-Tails Chakra Mode, Killer B advised Naruto to use his chakra arms instead to attempt to create a Rasengan. The results were incomplete, though they looked like a combined version of the Rasengan and Tailed Beast Ball.

At the start of his training Naruto finds some difficulty making the ratio of black and white chakra 8:2. Despite the fact he has a chakra shroud while practicing the technique, Naruto's hands are shown to be injured as he practices. He asks Killer B to watch and tell him when he has got the ratio right so he can remember the feel of the technique.

Naruto has also noted that this new Rasengan is quite heavy, as he can barely hold it up. This is likely because of the Nine-Tails' chakra, which has been described as very dense in previous instances. According to Killer B, he has almost perfected it, and the best way to learn and master it was from real-life experience on the battlefield.

Trivia

 * The positive and negative chakra are coloured differently in the anime, with red for negative and blue for positive.