Summoning: Impure World Reincarnation

The Summoning: Impure World Resurrection is a forbidden technique used to revive the dead. It was originally created by Tobirama Senju and later completed by Orochimaru. Kabuto now claims to have mastered it to a degree even higher than them. Kabuto also claims that the technique poses no risk to the user.

To perform this technique, the user must first acquire some of the DNA of the person they intend to revive. 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 revived must also reside in the "pure world"; victims of the Dead Demon Consuming Seal, for example, cannot be resurrected. Next, a living sacrifice is required for the soul of the resurrected to use as a vessel.

Once all the requirements for the technique have been met, the physical remains acquired are smeared on a special scroll and once the scroll is activated, the remains spread out in the form of a special symbol with the living sacrifice in the centre of the symbol. Then dust and ash encases the sacrifice's body, giving them the same appearance that the revived had at the time of their death. The person is then revived and the end product is usually stored in a casket until summoned by the user. The user can theoretically revive a limitless number of people in this way, so long as they have enough sacrifices and chakra to perform the technique.

When first summoned, the body of the resurrected appears gray and in a state of minor decay. They retain their personality, memories, and all abilities they had in life, including kekkei genkai. They can be restored to a closer likeness of their original appearance by the application of a special tag. This tag can also remove their personalities, binding them to the user's will, but to what extent is up to the user. Kabuto prefers to exercise only minimal restraint over those he revives, but this is very demanding on him and it is often simpler to completely eradicate their personalities, which makes them easier to control.

The revived are impossible to kill by normal means. Any damage they receive will regenerate, be it lost limbs or complete disintegration. Not even killing the summoner will get rid of them. There are only three known methods to defeat the technique: Once any of these methods is accomplished, the bodies turn back to ash and dust, with the bodies of the individuals sacrificed lying among the ashes.
 * 1) Seal away the soul.
 * 2) Have the summoner end the technique. As they are unlikely to do this voluntarily, using a genjutsu to trick them to cancel the technique is ideal.
 * 3) The revived is affected in some emotional way that gives them closure.

Trivia

 * When Kabuto first approached Madara about joining forces, he summoned Deidara, Itachi, Kakuzu, Nagato, and Sasori as a demonstration of power. When Madara threatened to refuse Kabuto's offer, Kabuto summoned a sixth casket that compelled Madara to not only join forces with Kabuto, but to call him a "Madman!". The contents of the sixth casket were obscured.