THE TWO FORMS OF REANIMATION

The Summoning: Impure World Reincarnation 

(, Kuchiyose: Edo Tensei) is a forbidden technique where, using a living person as a vessel, a deceased person's soul can be called back to the world of the living and bound to it. The vessel will then take on the form that person had in life, thereby reincarnating them to do their summoner's bidding. .It was originally developed by Tobirama Senju. Madara Uchiha claimed it to be intended for the dead to be reincarnated into soldiers able to clear a battlefield with devastating and otherwise suicidal attacks. The technique was learned by Orochimaru who modified it for his ends.Orochimaru's aide Kabuto Yakushi claims this technique to be the greatest and most powerful technique in the shinobi universe due to it posing no risk at all to the user, and mastered it to a greater degree than the previous usersTo perform this technique, the user must first acquire some of the DNA of the person they intend to reincarnate. Kabuto remarks that this basically amounts to grave-robbing, although blood stains or organs salvaged after the target's death also work. The soul of the intended reincarnated must also reside in the pure world  for example, those whose soul has been consumed by the Death God cannot be reincarnated. However, if it is a case where the souls are freed from inside the Shinigami, then a user of this technique is free to reincarnate them once again.Next, a living sacrifice is required for the soul of the reincarnated to use as a vessel. Once all prerequisites for the technique have been met, the acquired DNA of the person is smeared on a special scroll and once the scroll is activated, the remains spread out in the form of a special seal with the living sacrifice in the centre. Then dust and ash encase the sacrifice's body, giving them the same appearance that the reincarnated had at the time of their death. The process is apparently somewhat painful as seen when Fū was used to reincarnate Torune. The person is then reincarnated and the end product is usually stored in a casket until summoned by the user. The user can theoretically reincarnate a limitless number of people in this way, so long as they have enough sacrifices, chakra and DNA to perform the technique. Despite this, this technique also has limitations, such as the individual having limitations that inhibited them in life such as Nagato's lack of mobility and depending on the summoner's mastery of the technique, the reincarnated individuals might not be brought back with the full power they had in life.

Orochimaru performing the edo tensei to reanimate the previous  hokages

OUTER PATH(SAMSARA OF THE HEAVENLY LIFE  TECHNIQUE ):RINNE TENSEI

By channelling their power through the King of Hell, the Rinnegan wielder can re-infuse new life force energy to 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 technique targets all the individuals killed, even those not necessarily killed by the user. This technique seemingly requires a massive amount of chakra, as Konan feared the worst for Nagato when he used it after having previously expended so much chakra. Nagato also became severely weakened, his hair became increasingly thinner and greyer as he performed the technique.

• Madara Uchiha — 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 a jinchūriki, which he wanted to do with the Ten-Tails.
• Because Madara has been reincarnated and not revived, he needs Obito to perform this technique so that he can become the Ten-Tails' jinchūriki. Obito has noted that this would result in his own death, however.
• When written as Rinne Tensei means "the circle of transmigration"
  
  
   NAGATO USING RINNE TENSEI TO REVIVE THE DEAD NINJAS IN THE HIDDEN LEAF VILLAGE
  
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