Summoning: Impure World Reincarnation

 

 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, claiming that 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, mastered it to a greater degree than the previous users. To 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 (浄土, jōdo); those whose soul has been consumed by the Death God, for example, cannot be reincarnated. 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.