As one of the oldest lifeforms in this world,
the Mourning Tree's life form was exceedingly primitive.
Therefore, the Yuanling affinity of the Ancestor Wood was terrifyingly high.
As a quarter of the Ancestor Wood's root system, Quercus naturally inherited this trait.
The method of "killing" itself came from Sabellia.
To be precise, it stemmed from the research of Barry Gittler.
With even greater control than Barry, Quercus completely separated its consciousness, soul substance, and even its body—that is, the tree itself.
Then, it distributed its soul substance among its "friends," aiding them in growing into "boss creatures."
Following that, they summoned a plethora of lost souls from the Netherworld to create a massive Spirit Puppet, wherein Quercus concealed itself to evade the allure of the Shadow Realm and the Netherworld.
This colorless tree was born in this manner.
Its vitality shielded by the Spirit Puppet, which was itself inherently a lost soul.