Question: I am writing a fiction. In that, a woman is married to a man. The man is extremely strong, but extremely bad also. He does too much bad with his wife. In fact, the wife settles down to agree to a big number of his points; because if she would disagree he would burst her skull open. He is not like "MANY" other husbands; he is like those "FEW" husbands who think a wife has to say yes in coordination with all the husband's "YESes" and she has to obey all his commands. And if she refuses, the husband would hit her very hard. He does other big number of bad things with his wife also, but those I am not writing here; would write those in the story. Now, in my story the wife definitely punishes her husband and she punishes him in this way:
She laces his eatable(s) or ingestible(s) with such the substance(s)(ingestible) due to which he becomes irreversibly extremely weak. "HE BECOMES SO WEAK THAT EVEN AN EXTREMELY WEAK CHILD OF 12 YEARS CAN BEAT HIM IN PHYSICAL FIGHT". ... And then he dies. But the path thru which he dies is: He becomes irreversibly weak(physically, cannot win against anybody in physical fight), dies. This is not a harsh punishment for the husband, because I have not mentioned that what bad deeds the husband does with wife. I would write this story on the women whose husbands torture them on the basis that they are physically stronger than their wives.
Special Note:
(1.) Tell me the substance(s) which appear to be possible according to the proceeding of the story. Do not tell me the substance(s), which if the wife gives to the husband then he has such an effect that he comes to know that something has been given to him. Do not tell me the substance(s) which would be the bad choice(s) for the wife to give to husband. He must not be able to know that wife is giving something to him, otherwise the story would be spoiled.
What I mean to say is do not tell me the substance(s) like muscle relaxants which are used during anaesthesia. It's a bad choice because:
1. These have TEMPORARY effect.
2. Bad choice for a story because the readers would laugh at the story, because the basic theory of the story would be changed. The woman would be caught and the villain(the man) would win. When muscle relaxants which are used during anaesthesia would be given to the villain, he would have a feeling of the paralysis in his body, strong relaxation and he would visit a doctor and the female positive character who was tortured would be punished, which is unacceptable. So, do not tell such type of substance(s).
Overall, the question is that:
Which are the substance(s)(ingestible), which an XXXXXXX housewife gives to his extremely strong and bad husband to make him extremely weak(the strength needed to physically fight with an another person reduces silently and too much), to kill him. The weakness must be irreversible but a point is to be taken care of that the substance(s) should not effect the man in such a way that he comes to know that something is being given to him(e. g., muscle relaxants which are used during anaesthesia). The substance(s) must not put any such visible effect on the husband. The substance(s) must be real to make the story look real and interesting and should look possible for an XXXXXXX housewife to arrange or make at home easily. This is a question to the doctor(general physician) especially. But other doctors(i. e., a neurologist, a cardiologist etc.) may also answer this question.