Immortal Gu

Inside Hu Immortal blessed land, the land spirit can seal any rank one to five Gu worm at will. Only rank six Immortal Gu worms can move freely there. ^{ch. 372}

A mortal cannot activate an Immortal Gu easily. With land spirit help, immortal essence can pour out so the Gu fires when primeval essence alone cannot sustain it. ^{ch. 392} Immortal Gu are difficult to find. No matter how many mortal Gu a group of Gu Immortals holds, that stock cannot match a single Immortal Gu, and their thirst for Immortal Gu is extreme. ^{ch. 460} Immortal Gu are unique once they are created. ^{ch. 469}

Man is the spirit of all living beings and Gu is the essence of heaven and earth, a vessel of the Great Dao. If a mortal Gu holds only a tiny fragment of the law of heaven and earth, an Immortal Gu holds a corner of the Great Dao, an intact piece of those rules. Because of that, there can only be one Immortal Gu of its kind. Every time an Immortal Gu is born, other Immortal Gu in the surroundings tremble and respond. ^{ch. 564}

High grade blessed lands leave leftover heaven and earth qi that can mutually interact and refine a mortal Gu into an Immortal Gu. ^{ch. 609} When a mortal Gu becomes an Immortal Gu, the change is a dangerous qualitative jump that involves heaven and earth qi and can form the corresponding heavenly tribulations and earthly calamities. ^{ch. 610}

Ranks one through five Gu are covered on Mortal Gu. Gu as living tools are covered on Gu worms. Immortal essence as fuel is covered on immortal essence.