A set of ingredients for refining an Eternal Dao Union Pill.
That tempted Lin Fei somewhat.
Back when he was on Medicine Mountain in the Gu World, he had gathered quite a few immortal-grade spirit herbs and medicinal plants, but the one thing he had not obtained was an Origin Return Dao Heart Fruit.
The Origin Return Dao Heart Fruit.
It was the main ingredient for refining an Eternal Dao Union Pill.
According to the records in the Holy Demon Sect's Cosmos Mirror, Lin Fei knew two methods for refining the Eternal Dao Union Pill.
The first used a "Human Immortal's primordial spirit" as the main ingredient, combining it with various spirit herbs and medicinal plants to refine the pill.
Something like the Ten Thousand Souls Ancient Willow's "ten-thousand-year willow heart" could also be used, with roughly the same effect.
But this method was not only rather sinister; obtaining the main ingredient was also extremely difficult.
After all, to refine a pill using a Human Immortal's primordial spirit, one first had to capture an Eternal Giant in the human immortal realm alive.
This method of pill refinement was also known as "human pill refinement."
Refining people into pills was considered an evil, demonic practice by some immortal cultivation powers, and was reviled by all.
Some weaker immortal cultivation powers opposed this method precisely because they feared that one day, some mighty immortal cultivator might set their sights on them and capture them to refine into pills.
The second method was orthodox pill refinement.
There were three pill formulas in total.
The various supplementary ingredients could be substituted, but the main ingredient was always the Origin Return Dao Heart Fruit.
Lin Fei did not know whether other immortal cultivation powers possessed Eternal Dao Union Pill formulas that allowed other immortal-grade spirit