I read he lost his immortality and became mortal when HQG broke the seal he put on her when he tried to hide the fact she had the Demon God power in her. When HQG was so grief stricken by the death of those she holds dear, she broke the seal and became Demon God. That was when BZH loss all his power. He can still fight and all but he is now mortal as in no longer immortal.
I read he gained back his immortality by kissing HQG before her death, drinking her blood. So he became immortal again. But remember even immortals can be killed. Immortal means you live forever, won't age unless you get killed. In her dying moments she used her goddess power to curse him to a truly immortal status, meaning he won't die no matter what. He won't age plus nothing can harm him. So he can't even kill himself.
TV version.
I read it will be different, of course.
Rumours has it BZH gaining his immortality back is thanks to Zixun. I don't see how that is done so we shall see! As for the curse, it won't happen. But maybe it will in a different form.
HOW IS HQG REVIVED AT THE END
Book version.
She got stabbed by Mingsheng Sword and supposedly her soul, everything is gone. But SQM saved a sliver of her dispersed soul. BZH went mad for either 30 or 300 years, depending on which sadistic version you are following looking for HQG and even killing innocent people that people got very scared of him and when he knew SQM had a fragment of her soul, he went in search of SQM to beg SQM to release that soul to be reincarnated. Something like that. What we have then is HQG now dumb or not all there ad bullied and BZH adopted her as his disciple again and they were together again and contented and afraid one day she might remember her past because before her death she wished she had never fallen in love with him. In many epilogues, one of which I feel if this series was properly shown may have used that ending got to do with a reincarnated DFYQ (who in the book can't live past 25 years old and will be reincarnated with all memories of previous lives intact) and HQG gaining her memory or something like that. Not sure. Point is BZH and HQG will end up together.
TV version.
Rumours has it HQG's revival has something to do with Mo Yan and I hope it is true although I don't see how. HQG did die but no curse, no soul dispersed and definitely no reincarnation. Apparently Mo Yan will sacrifice himself to revive HQG who had no memories and so retire happily with BZH. I hate the no memories part. As if everyone who had sacrificed for her didn't matter as long as she gets to kiss and hug and sleep with BZH as husband and wife. Sorry that's how I feel. I hope she gets her memory back and CHOOSE to stay with BZH. And if Mo Yan does sacrifice himself .. well I posted the following in the forum for the logic of this ending:-
I suppose.. and I never read the book but series wise.. he feels paternal but he is wrong about his feelings which is beyond paternal. he feels responsible for her, blamed himself for whatever she is, whatever she had done,w hatever she had to endure, so he was willing to take on her suffering with her but due to his principle and position, he can't be living with her because remember, at this point he feels he is her shifu and no more.
Much like No That I Love Ceaser less But I Love Rome More aka Not that I love Xiaogu less, but I love changliu more. He can't do things that is gonna be against changliu and if he does live with her, imagine what mo yan and other sects will do. They will attack Changliu and will charge to kill HQG, etc.
So I get him. What I don't get is why don't just prior to the nail punishment just let her run away with SQM? DFYQ is not powerful enough to fight all sects, SQM can do it. Even if HQG doesn't want to, he can just stab her with his sword (lightly) and throw her out. And yet he can't do it. He can't even disown her openly.
His compassion misled him. His kindness hurt him. Now his love will ruin him.
He still cares too much what others think. At the end his way of happiness is to disregard everybody else, to turn his back from the world, to turn his back from his 1000 years of cultivation and order in life and his love for changliu and leave with HQG. NOW that is extreme but I suppose if the spoilers are true with MY doing the sacrifice, in the end if he got the approval of the one guy who is dead set against them, that is his pass to leave changliu. Maybe MY will realise if he had not pushed ZR's mom away (or kill her or whatever) he would be less grumpy so maybe his last words will be
"Zihua, I was a fool. Do as your heart desires. Don't worry about Changliu. Find your own path, your own happiness" and DIE!
If the spoilers are wrong, then I am interested to know the growing list of questions;
1. how to solves BZH's mortality back to immortality
2. how to revive HQG (and please stop with the nonsense loss of memory-what an insult to all who sacrificed for her. She is not the most pitiful person)
3. New question. to to make BZH's exit from changliu justified; with approval, and without just turning his back on the world. Key is I believe Mo Yan perhaps. I don't know. Love isn't everything. The idea to allow BZH to exit Changliu must be graceful and justified if not I will lose all respect for him.
It has to be graceful, graceful means without hate, without anger, without regrets, without being forced to choose sides that he is allowed to go. I think SXM can give him that go ahead but none more powerful than that of MY's approval. So I like the idea of MY being the catalyst but I am not sure who he will revive HQG in the process. So series gotta explain! If this is true. No fans will blame BZH from just leaving. That's what they want him to do. But I like a better ending where the idea is he can retire happily and unretire one day and the only way is to leave changliu with consent.