Cursed Seal of the Celestial Oath

The Cursed Seal of the Celestial Oath is a powerful juinjutsu employed by Saimei Ōtsutsuki to her subjects.

Appearance
The cursed seal itself takes off partially from Saimei's coat of arms, with several magatama circling around two more circles, with markings displayed in-between the magatama and circles, and single black circle in the middle with an horizontal Ōtsutsuki Clan symbol engraved on it. The markings in-between the circles spread all over the body whenever the cursed seal is activated by the user, much like Orochimaru's Juinjutsu. The cursed seal is usually placed on the chest

When combined with senjutsu chakra, the markings widen to cover the whole body and turn white, and horns grow on the user's forehead, in semblance to a Ten-Tails jinchūriki. The remainder of the cursed seal grows to encompass most of the torso area and glows in a teal tone, even through clothing; a marking similar to Hashirama's Sage Mode also appears on the forehead, as well as black pigmentation around the eyes and the irises changing to white in color.

Usage
As with Orochimaru's cursed seals, the user receives a tremendous chakra and physical boost when activating the seal, however, it's main function is to bind the user's soul and chakra to Saimei in order to prevent treachery. This cursed seal has been applied to most, if not all, of Saimei's soldiers and servants.

Another effect involves a degree of immortality, as the user's soul and chakra remained bound to Saimei even after their physical death, consequentially imprisoning the user in the mortal plane until their task is done or Saimei releases the cursed seal herself. While what this "task" exactly consists of is very ambiguous, it's usually associated with the user's feel of having served Saimei faithfully and having fulfilled their role, so it is possible for one to release the cursed seal on their own if they possess this mindset.

When combined with senjutsu chakra, the cursed seal evolves in a manner yet again similar to Orochimaru's cursed seals, in their second stage, granting the user a unique Sage Mode.