Big Ball Rasengan

The Big Ball Rasengan is a more powerful version of the Rasengan.

Overview
In the anime, Naruto created the Big Ball Rasengan during his two-and-a-half years of training with Jiraiya; while training to break out of genjutsu, Naruto accidentally released his chakra and created a huge Rasengan. It uses the same concept of compressing spinning chakra in one's palm as in the original Rasengan, only increasing the amount of chakra involved. Because there is even more chakra being compressed to a higher density, the ball releases its energy immediately on contact, thus increasing its destructive power beyond the Rasengan's.

When Naruto first starts using the Big Ball Rasengan, he needs a shadow clone to help him form and wield it. He is able to wield it with one hand when his skill with it improves, though he still needs a clone's help in its formation.

Usage and Improvement
Like the Rasengan, Naruto improved the Big Ball Rasengan and created a variant with his Nine-Tails Chakra Mode. The size and power of his Big Ball Rasengan also improved, with it growing to nearly half the size of the Ultra-Big Ball Rasengan. He can also add Wind Release to it, to create the Big Ball Rasenshuriken.

Senjutsu Influence
When in Sage Mode, Naruto can use a senjutsu-enhanced version known as. As with the original, Naruto uses a shadow clone to help him form the ball. With this senjutsu version, however, he can have a shadow clone form a Big Ball Rasengan in each of his hands, which he can then pass to the clones for them to wield. The Sage Art: Big Ball Rasengan is much larger than the original, almost being as big as Pain's summons.

Trivia

 * Minato Namikaze's normal Rasengan is roughly the size of the initial Big Ball Rasengan. In fact, he could use this technique in Jiraiya's novel within Tsunade's Infinite Tsukuyomi dream.
 * By the end of the Fourth Shinobi World War, Naruto's regular Rasengan has increased to the size of the initial Big Ball Rasengan.
 * When Konohamaru used this technique in an OVA, he was able to use it with one hand.