Primeval Essence

A Gu Master is someone who has opened an aperture and uses this essence to feed, refine, and manipulate Gu. ^{ch. 7} Inside the aperture the fluid forms a primeval sea; every drop of that seawater is pure primeval essence, the condensation of the owner’s essence, vitality, and soul. ^{ch. 6 ch. 10}

Spending and recovery

Essence is precious because it is the source of power for refining and using Gu. When Fang Yuan refines Moonlight Gu, a jet of essence leaves the sea and rushes into the worm; while the Gu resists, that essence can be driven back out and the gain erased unless he keeps refining and replenishes the sea. ^{ch. 10}

Two ordinary ways restore spent essence. Natural recovery refills the sea over time: for a C grade talent about four percent of the aperture’s store per hour, or about twenty-four percent in six hours; for an A grade talent about eight percent per hour, forty-eight percent in six hours. ^{ch. 10} Primeval stones are the external supplement. A Gu Master can extract essence from a stone to raise the sea’s water level, so stones are both currency and cultivation fuel. ^{ch. 8} Talent still caps how high the sea can stand: Fang Yuan cannot store past forty-four percent even when empty space remains above the surface. ^{ch. 10}

Color and density by rank

Rank five essence