My Main Antagonist is a Ghost/Evil Spirit so How Can I Kill Her?

[scink]

Please help, I put myself in a corner.

So here goes. As my story progresses, it will be revealed that the main antagonist is a dead soul who was once a fire magic user. she was once a powerful magic user but in her time, women are oppressed so she was also belittled even though she was reaaally powerful. When women tried to fight for their rights, she was one of the people who openly protected those women. in the end she died. to appease the souls of those women who died fighting for their rights, the then king gave their families money to compensate for their deaths.
Main Antagonist (MV)'s family was given a large sum of money that can live luxuriously for generations and a big house. mainly because she was a great fire magic user when she was alive so they kinda took her accomplishments in consideration.
Years past and where now in the timeline of the story. There will be villains that the MC will face and win against but when she thought everything was over, MV strikes. She seeks revenge because first, her descendants are living miserably (shabby house and poor health). she thinks that the royal family neglected her family and the promise of taking care of her family was only fulfilled in the beginning and was just all talk. but in reality, her family were gambling addicts and are the ones who misappropriated their money. Second, she thinks that it is unfair that she suffered her whole life while the princess was spoiled and pampered even though she is useless. everything mainly roots from her hatred and jealousy.
How can I kill a dead soul who doesn't have a physical body nor something that can kill her as she is already dead?

First you would have to explain how a ghost without any physical form could endanger anyone. The best she could do was frighten folk. If however she is able to transcend the etheria then maybe she has a mortal core that can be trapped. So there would need to be a counter to her powers and this may simply involve a way of inverting reality and casting the hero of your story into her world. Or other way around. They meet in fires of burning red embers where all around is black and white. And the core of her power is extracted as she surrenders to the warmth of his passion.... The twist is that the hero can never return and is cast into the nether by his actions as his loved ones watch as he is consumed by fire. The family stand on the hill gazing on as the house burns to the ground from the ensuing flames. Or something like that.

 

[S.T. Ockenner]

First you would have to explain how a ghost without any physical form could endanger anyone. The best she could do was frighten folk. If however she is able to transcend the etheria then maybe she has a mortal core that can be trapped. So there would need to be a counter to her powers and this may simply involve a way of inverting reality and casting the hero of your story into her world. Or other way around. They meet in fires of burning red embers where all around is black and white. And the core of her power is extracted as she surrenders to the warmth of his passion.... The twist is that the hero can never return and is cast into the nether by his actions as his loved ones watch as he is consumed by fire. The family stand on the hill gazing on as the house burns to the ground from the ensuing flames. Or something like that.

Or maybe she's a poltergeist? Or psychic? Or she can possess people/objects?

 

[Darkfantasy]

Maybe the ghost could be contained for eternity instead. Or there is a weapon that can kill a ghost. Or someone that is a "ghost slayer".

 

[Mari More]

First you would have to explain how a ghost without any physical form could endanger anyone. The best she could do was frighten folk. If however she is able to transcend the etheria then maybe she has a mortal core that can be trapped. So there would need to be a counter to her powers and this may simply involve a way of inverting reality and casting the hero of your story into her world. Or other way around. They meet in fires of burning red embers where all around is black and white. And the core of her power is extracted as she surrenders to the warmth of his passion.... The twist is that the hero can never return and is cast into the nether by his actions as his loved ones watch as he is consumed by fire. The family stand on the hill gazing on as the house burns to the ground from the ensuing flames. Or something like that.

Hi!
"First you would have to explain how a ghost without any physical form could endanger anyone."
-the answer to this is because of the magic/element that is dominant in my world. Magic users that have fire magic/element can manipulate passion, desire, emotions (aside from the obvious fire elements like fire and heat). The Main Villain(MV) is a powerful fire magic user even though she already died and "lost" her powers she can still somehow influence people's emotions. First she influenced those who are jealous and hates FC and those people around her (some got influenced and some didn't). At first, no one knows that she was behind everything. she only showed herself after the "main antagonist" (not really the main antagonist, no one knows that a ghost is the REAL main antagonist or the final boss) died she had no choice but to do everything herself.

Now that I've seen all of the answers here, I realized that I think I've been too focused on how to "kill" an already "killed" character. I didn't consider to conceal her or something because I think that by doing so it will only put everything on end temporarily because she might escape in the future or someone might free her. but in the end, containing/jailing her is the only plausible way to defeat her because I created her character that way(a ghost/evil spirit) who's basically non-killable. All I need to do now is to contain and put the strongest containing spell I could think of to prevent her from escaping or being freed.
If you have any suggestions, feel free to comment it down below

 

[Toby Johnson]

well... you cant exactly kill her is you are sticking to the laws of spirits and medium. but this is fantasy so you could invent a way that she could be killed like bury her again in a lead coffin. but if you want to stick to the laws of spirits in our human realm, then you cant kill her but you can capture her in a hand mirror.