Law of Pure Emptiness
Nirvana is an ancient force that permeates the universe, just like fate, karma, entropy, and genesis. Its ultimate goal is to break the endless cycle of rebirth and grant eternal peace to broken and old spirits.
This was a power some people considered a curse, a cruel joke of the universe. The goal of all powerhouses is to reach eternal life. All of them hope for rebirth once their life force is reaching an end. However, the number that obtains it is almost null.
Nirvanic Rebirth is a law bound to the phoenix bloodline. It allows a being to undergo a form of rebirth and rise even more powerful than before. This law's ultimate goal is to grant a soul and body that cannot be harmed by the power of Nirvana.
There is a reason it can aim at such a lofty boundary, and that is because the Law of Nirvanic Rebirth is older than the current universe.