Deceiving the Dead and Defiling the Ancestral Rites

[Villain protagonist, decisive and ruthless, original xianxia setting, expansive worldbuilding, plotting for dominion, no transmigration or rebirth, not a single heroine] The Cloudtop Purple-Gold Palace. What a cursed thing it is... Who knows how many people devoted their lives to arduous cultivation, slaying demons and saving the people, only to meet a bitter, bloody end because of it? And yet, without it, how would there be immortals in this world to slay demons, save the people, and bring peace? As the little junior sister listened to an old man speak, she remembered that her senior brother had mentioned this object too. Come to think of it...what did her senior brother want with the “Cloudtop Purple-Gold Palace”? He had even declared that he would pay any price to obtain it... The little junior sister was deeply puzzled. But no matter how puzzled she was, it did not stop her from staying close to her little senior brother, the one the whole world called a “brute.” Strangely enough, this brute was utterly vile, cold-blooded, and willing to use any means to achieve his ends... He might even see his devoted little junior sister as little more than a pawn. He was also a shameless womanizer, toying with peerless beauties and prodigious goddesses alike. Yet the little junior sister did not care in the least: “If my little senior brother is willing to treat me well for the rest of my life, then I can remain blissfully ignorant.” Note: There are many plot threads planted early on, so parts may be a little confusing at first. They will all be explained later, so read on with confidence.