Mystic Nature Art was a cultivation technique meant for cleansing oneself. The goal of this cleansing was to be a Mystic Human.
Therefore, any existence that gains knowledge of this cultivation technique has a year left to live. By then, they must succeed in becoming a Mystic Human or die trying.
A Free Human who hasn't practiced any cultivation techniques has a small chance of becoming a Mystic Human within a year. Free Humans with existing Human Avatars had a chance extremely close to zero.
For Pranic Beasts, gaining knowledge of Mystic Nature Art was pretty much a death sentence.
For Mystic Humans, cultivating Mystic Nature Art allowed them to build up their magnitude of resistance. The greater the magnitude of their resistance, the easier and quicker they could resist external influences.
