Fire Release: Second Rebirth Technique

The Second Rebirth Technique is credited as the ultimate non-kekkei genkai Fire Release attack. It is a forbidden technique that can revive the dead.

Background
In the past, the First Mazuka lead Yamagakure into war during the. During the war, he faced the and his Summoning: Impure World Reincarnation technique on the front lines. Needing a way to combat this technique, the First used his incredible mastery of fire-type ninjutsu and developed this technique, which could completely eradicate the Impure World Reincarnation technique.

Overview
In order to use this technique, the user must've killed a large amount of enemies with Fire Release techniques. By stabbing a sword or some other medium into the ground and then activating this technique, the ashes of those victims begin to rise and reconstitute themselves into a skeletal-like form; resembling zombies. Like with Impure World Reincarnation, the revived retain any weapons and techniques they possessed in life, however, since their souls are not bound to their bodies in this technique, they lack their personalities and their bodies beyond the skeletal state.

If the revived are destroyed in combat, the flames used to bring them back will regenerate their bones and bodies, allowing them to continue fighting. While the number of revived vary from user to user, the First Mazuka was able to revive thousands of victims at a time because of the great many people killed by his Fire Release techniques, leading to the technique earning the moniker "grand army of ten trillion dead and buried by flames" (火火十万億死大葬陣, kaka jūmanokushi daisōjin).

Weakness
The technique is not as absolute as the Impure World Reincarnation technique. First and foremost, if the user is killed, the revived disintegrate and the technique is ended. The zombies can be sealed, just as the revived from the Impure World Reincarnation can. The technique can also be forcefully ended with a Contract Seal. This is because the undead, brought back by this technique, are connected to a summoning contract which was created when the revived shinobi's original body was killed by the user's fire techniques.

Trivia

 * It shares its moniker of "strongest Fire Release" technique with Amaterasu.