Yin Wood, possessing exceptional spirituality, is a precious and rare tree species. Whether used to concoct the Potion of Immortality or to refine peerless divine weapons, even a small bit of Yin Wood can significantly increase the success rate.
It is said that Yin Wood grows in the Underworld, an inch in a hundred years, a foot in a thousand years, and no more than ten feet in ten thousand years. The ten-foot-tall ones are as red as blood agate, the thirty-foot ones are as clear as amethyst. The longer they grow, the more spiritual essence they contain.
However, even in the so-called Underworld, Yin Wood is rare to come by, let alone the blood agate and amethyst varieties.