I suggest watching the anime...everything makes more freakin sense after you watch it
But here's a small breakdown....there were originally 5 great clans and one clan, the Wen clan, became evil and started overthrowing other clans, so the other 4 clans overthrew the Wen clan. Wei wuxian or the Yiling patriarch was part of one of the 4 clans, their clan got wiped out by the Wens. He was thrown into a burial mound and he started using resentful energy as a means of cultivation.
With that, he's able to control feral zombies, spirits and the likes with the Stygian Tiger Seal, he lost control of it and killed a bunch of people but before his death he destroyed the seal. He is looked upon as an evil person but there's like...some more backstory to it...so just watch the anime
It's best if you watch the anime/donghua then read the novel. Audio drama is another good way since it's very accurate. Some arcs need a rereading since there are hints that are easily missed.
reading the novel actually helped me a lot after watching the live action drama and anime, so maybe you should try this if you like to read in general?
Nie Mingjue is the leader of his clan. he is the big bro of Nie Huaisang, one of the best friends of Wei ying (main MC of the story)
right now we see the point of view of Nie Mingjue and what happen to him before his death. and MC watch his life story like a movie.
the Wen clan are the enemies of almost everyone and the MC.
i dont know who these people are i genuinely cant remember them. if someone can give me a tl:dr thatd be appreciated