There was a folk-tale about one immortal cultivator. He was the one who sealed Burial Mounds so that the demons and evil spirits that live there wouldn't see the sun of the new day ever again.
But for him to successfully seal all the evil beings in Burial Mounds, he had to seal himself with them. They are torturing and tearing his soul and body apart even to this day. He has no way to escape.
Because of his selfless sacrifice, the humans were able to keep living, cultivating and dealing with corpses of their caliber. Because of this, whole world knows the name Yiling Patriarch. He was and still is worshiped by many. Unfortunately, his real name was not passed to the next generations and was forgotten forever.
Everyone knows that there is no way to escape the terror in Burial Mounds, the same terror he is suffering now. No one ever dared approaching this cursed place.
Of course, except for the mighty Wen Clan who wants to rule and to rebuild the world into an image of its own. What they did not know when they went to the Burial Mounds to find the source of new power - of the demonic cultivation - and all the resentful energy in this world was, that they will wake up one and only - very pissed off - immortal from old legends.
Who may or may not be one of the most beautiful things in this world one could ever seen.