The Ultra-Big Ball Rasengan is a more powerful version of the Big Ball Rasengan (which is stronger than the standard Rasengan).
In an instant, the user creates a Rasengan of gigantic proportions, larger than their own body. When it impacts, there is a large shock wave unleashed that can send unsuspecting shinobi flying. As with many Rasengan-variants, Naruto needs the help of a shadow clone in the Ultra-Big Ball Rasengan's formation.
When in Sage Mode, the user can perform a senjutsu-enhanced version known as Sage Art: Ultra-Big Ball Rasengan (仙法・超大玉螺旋丸, Senpō: Chō Ōdama Rasengan). Although it has not been successfully used in the series, it is said that its destructive power – were it to explode – would easily carve away an entire mountain.