Outer Path — Samsara of Heavenly Life Technique

By channelling their chakra through the King of Hell, the Rinnegan wielder can re-infuse new life force energy into the bodies of those who have died. With their rejuvenated bodies acting as an anchor, the individual souls are then able to leave even the crossroad between life and the afterlife, returning back to their physical vessels. The range and power of this technique are currently unknown, but so far it has targeted either all the individuals recently killed, or a single individual who has been dead for more than a decade.

This technique can also be used on people brought back to life using Summoning: Impure World Reincarnation, transforming the debris and ash that forms the corpse vessel into a real body of living flesh and blood; even if they have been dead for many years. However, they would be revived close to the state they were in prior to their death. Madara, for example, did not have his original eyes upon him during his passing and was resurrected without them.

This technique seemingly requires a massive amount of chakra, risking death in the process, as Konan feared the worst for Nagato when he used it after having previously expended so much chakra. After using the technique, Nagato was severely weakened and his hair became white due to overexertion of his chakra. Using this technique to revive a reincarnated person will result in the death of the user.

Influences
As with many of the Rinnegan's techniques, it is influenced by Buddhist terminology. , derived from the Sanskrit Tīrthika, refers to any doctrine which "treads the outer path" to enlightenment. This is opposed to the teachings of orthodox Buddhism, the, and is thus considered misguided and heretical.

Trivia

 * Madara — and Obito under the guise of Madara — noted that this technique was supposed to be used to revive him. Madara would eventually be reincarnated anyway, and expressed surprise and disappointment that his return didn't go as planned, as only a living body can become the Ten-Tails' jinchūriki. Eventually, Black Zetsu successfully forced Obito to perform the technique on Madara.
 * When written as '輪廻転生', Rinne Tensei means "the circle of transmigration".