
Cursed Seals
The Curse Seal was developed by one of the Legendary Sannin, Orochimaru. The seal is used as a form to control the person and a technique to literally kill the person through suffering. A person with the curse seal only has a 10% chance of surviving. If the evil curse seal has consume a person's body, that person will gain tremendous dark chakra and increase their strength and speed, giving them level 1 curse seal. The curse seal can active at anytime. A person's will is able to stop the curse seal from spreading or active it.
To obtain level 2 curse seal, a person must lost his life, not actually died but fake death. The person will eat the Seishingan drug and is placed inside a container, sealed with seal symbol. The drug will make the person fall into a coma, much like near death. When the Seishingan drug have fully consume the person, that person has achieved level 2. Anyone that stay in level 2 form for a certain amount of time will lose themselves forever and become evil.
Sasuke Uchiha
Curse Seal
Sasuke's curse seal is known as the Heaven Seal. It is the strongest and powerful of all the curse seal. He received the mark during the 2nd stage of the Chunin Exam. It was merely a test for Sasuke to see how strong an Uchiha bloodline is.
Curse Seal Level 1
Sasuke achieved level 1 curse seal when the curse seal had consume his body. It took over his body during the fight against the 3 Sound Ninja, giving him big amount of chakra. The spreading of the curse seal will active the level 1 curse seal.
Curse Seal Level 2
After taking the Seishingan drug and placed inside the container, the drug was able to fully consume Sasuke and somewhat killed him. He must died to obtain level 2 curse seal. In this level, Sasuke light brown and grew longer hair and has 2 wings. This form makes his Chidori (Lightning Edge) turn black instead of white. Sasuke doesn't stay in this form long because he doesn't want to lose himself forever