Immortality

As implied by its name, Immortality grants the user the ability to prolong their life, effectively granting them the potential for an infinite lifespan. However, this technique is not "de-aging", meaning that the user cannot escape the physical changes brought upon by the process of aging.
Once a user of immortality reaches a certain age, the technique attempts to change bodies by undergoing an "evolution". This process causes the self-awareness and will of the user to cease to exist and they become a shell of their former self as a result. To prevent this, every five hundred years or so the user must merge with a capable "Star Plasma Vessel" and rewrite their body's information. Once the body is refreshed, the cursed technique follows suit and evolution does not occur.

Evolutions

Human:
Normal Start
Cursed Spirit:
They have evolved into more of a cursed spirit than a human. They have maintained their self-awareness but their very self has become the world in a sense
Hyper Evolved:
Unknown

Odd Nature

Tengen doesn't need to eat or drink. She has advantage on saving throws against Diseases.

Life Saver

Tengen has the innate cursed technique of immortality. Every time she is reduced to 0 points, she doesn't die but becomes Incapacitated until a long rest.

Legendary Resistance

If Tengen fails a saving throw, She can choose to succeed instead
Limit: 2 times each day