Orochimaru's Juinjutsu

Orochimaru's Juinjutsu are the cursed seals that were an often-used technique of Orochimaru in the series.

Overview
Due to extensive experiments to his own body, Orochimaru was unable to use Sage Mode and thus had to create an alternative way to make use of senjutsu. Orochumaru thus used Jūgo, whose body naturally produces an enzyme that triggers bodily transformations, and created a brand of cursed seals that would feed off the wielder's chakra and give them Orochimaru's senjutsu chakra. Because of this, the cursed seals are compatible with members of Jūgo's clan allowing those, such as Jūgo himself, to transplant some of his flesh to Sasuke.

Orochimaru usually gave his cursed seal to his most powerful and unique followers and guinea pigs to either make them his strongest warriors or to prepare them to become a potential host bodies in the future or simply as test subjects. To apply a cursed seal, Orochimaru usually bites his intended target. As he had sharp fangs and an extendible neck, this was a relatively simple task. The seal then appeared on the body of the victim near the puncture wound, which would cause them to subsequently lose consciousness. The design of the seals could either vary from person-to-person or was dependent on the type of seal Orochimaru chose to brand the victim with. If the victim had survived the application of the seal, they would awaken with the first level of the seal activated and enraged due to the seal's influence.

The cursed seals that are partially made from Orochimaru's chakra, also contain portions of his consciousness, and thus allows him to be revived when combined with a piece of his DNA to utilise the Evil Releasing Method on a host like Anko Mitarashi, Orochimaru can be resurrected completely even if his original body and self were destroyed.

For the anime-exclusive seals, they tend to have fatal side effects if handled improperly, as seen when Mizuki's seal, which is unique in that it requires extra procedures to activate its powers, he nearly died due to using it earlier than he should, and lost all his powers regardless. The ones administrated onto Team Guren would kill them if they do not take the required medication periodically, which prevents them from escaping Orochimaru's clutches.

Mechanics
The seal forcefully absorbs a user's chakra while giving Orochimaru's own senjutsu chakra into the user's body in return, granting enhancements comparable to those of Sage Mode. The user must also possess an above-average chakra capacity in order to wield the cursed seal's power. The key differences between the sage mode and a cursed seal are that the latter's users have no control over natural energy, thus senjutsu chakra in itself. The forced transformation seemingly eats away at the user's chakra to sustain its state, as Anko noted, with possibly fatal consequences. As long as a user has sufficient chakra to sustain the state, he or she would then obtain additional chakra to perform skills that would have been otherwise incapable of due to exhaustion. However, this additional chakra is separate and distinct from the user's own chakra, and techniques generated whilst in second level transformation assume a different colour. While the enhancements granted by the cursed seals are noteworthy, they mostly are inferior in comparison to those of Sage Mode.

Because the seals forcibly draws chakra from it's user, they will often kill the user when first applied. Orochimaru has averaged a ten-percent success rate when applying these seals based on his first experiment with his ten test subjects, with only one survivor, his student. Additionally, even if the users survive, their body will not be able to easily control the power of the seal given to them. To compensate for this, Orochimaru developed the Mind Awakening Pill. The drug forces a user's body to become accustomed to the unnatural increase in power, but also kills the one who takes it. The sealing technique Four Black Fogs Formation and Dark Sealing Method are used to keep the drug from killing the users by placing them in a temporary death state. Prolonged usage of the seals would also corrode both the body and mind of the users due to Orochimaru's chakra being present, making it easier for them to be susceptible to his influence.

Transformations
The seals have two different levels, and the types of transformations differ from seal to seal. When inactive, the seal is simply a black tattoo on the user's body. Orochimaru has a wide array of cursed seals, so the appearance and power of the seal will usually vary. Each seal always has three identical marks arranged in a circular pattern. When first activated, the marks on the seal glow and replicate, spreading over the user's body. This is known as the of the seal. The degree to which this occurs is dependent on the user, and the degree to which it spreads is proportionate to the overall effect it has. Normally, the wearer of the seal will also experience slight pains during the activation of this level.

The of the seal causes the black marks to completely envelop a user. This is followed by many unnatural alterations of the user's body. Once transformed, common features shared include yellow eyes with a black sclerae, skin changing colour, and longer hair. When in this level, the seal also eats away at the mind and personality of its users, driving them to madness if used for too long. It also takes quite a toll on their body, since they are being mutated by the seal. Aside from the first and second levels of the seal, skilled users of the seal are able to perform partial transformations in which the aforementioned mutation caused to the user's body in the level two state can be used without altering the entire body. The power of the cursed seal can even synchronise with the user's regular body with extended use, exponentially enhancing the abilities of their normal state.

Cursed Seal of Heaven

 * Wearers: Sasuke Uchiha, Anko Mitarashi

Cursed Seal of Earth

 * Wearer: Kimimaro

Sound Four's Cursed Seals

 * Wearers: Jirōbō, Kidōmaru, Tayuya, Sakon and Ukon

Orochimaru's Prisoners

 * Wearers: Ahiko, Guren, Takishi, Tsukushi

Animal Cursed Seal (Anime only)

 * Wearer: Mizuki

Team Guren (Anime only)

 * Wearers: Nurari, Kihō, Kigiri

Spiral Zetsu (Manga only)

 * Wearers: Spiral Zetsu