Once Upon a Time, There Was a Blade of Grass on a Grave

After transmigrating into a xianxia world, he somehow becomes a clump of weeds on an unknown grave! From the start, bugs are chewing on him, and his lifespan is counting down! Qin Shou furiously activates the evolution System: stronger roots, sharper leaf blades, venom secretion... Wait, who exactly is buried in this grave? Why are spiritual energy and Yin energy both rushing here? This life as a weed is getting more and more exciting!