Naruto blessed with Rasengan

The Rasengan (螺旋丸; Literally meaning "Spiraling Sphere") is a powerful A-Rank technique invented by the Fourth Hokage, Minato Namikaze. After three years of development, he never saw it completed, having never acheived the desired results before he died.

Minato's idea for the Rasengan was to take the Shape Transformation of his chakra to the "highest possible point" and then combine it with his chakra's nature affinity, creating a jutsu that didn't need the aid of time-consuming Hand Seals to control. He died before he could accomplish this, but, on shape manipulation alone, the Rasengan is still a very useful, powerful, and difficult jutsu to learn.

The Rasengan doesn't require any hand seals to use, relying only on the chakra control of the user. Once it's complete it becomes self-sustaining, which does not give Rasengan a definite limit like its counterpart, the Chidori. The compacted nature and moving speed of the chakra allows the Rasengan to grind into whatever it comes in contact with, inflicting major damage. This also tends to launch the target backward once hit. In an anime filler arc, Naruto was able to perform this jutsu as a mid-range projectile technique by somehow throwing it into a wall.

The Rasengan was designed to use the caster's elemental affinities. Minato was unable to add his affinities to his Rasengan before he died. Kakashi tried to add his lightning element to the Rasengan, but was unable to and explains that he uses the Chidori and Lightning Blade instead, which requires a certain point of shape manipulation and nature manipulation itself. Naruto was the first to add his wind affinity to his Rasengan and even advanced it to the point that he was able to create the Wind Release: Rasenshuriken.