Thousand-year Lifespan Gu

A thousand years Lifespan Gu increases a person’s lifespan by a thousand years. Lifespan Gu are extremely rare and sought after. ^{ch. 126}

Wood Charm fusion

Hundred-years Wood Charm Gu needs to fuse with a thousand years Lifespan Gu to advance into rank five thousand-years Wood Charm Gu. Everyone knows this fusion route, but Gu Masters rarely use it, because a Gu Master who finds a Lifespan Gu usually uses it directly to increase their own lifespan. ^{ch. 126}