Why does the Torah juxtapose the Parshah of a Mechashef to that of a Mefateh?
Oznayim la'Torah: Because if a man fancies a certain woman, he sometimes turns to a witch to cast a spell on her that she will agree to marry him.
What is the definition of a Mechashef?
A sorceress is Chayav Sekilah (Sanhedrin, 53b). Why does the Torah place a La'av against allowing her to live, rather than an Asei to sentence her to death,, as it does by other Chayvei Misah (See Shoftim, Devarim 17:7 and above, 21:12?
Ramban: Because of the deep Tum'ah that is inherent in sorcery, which, due to powerful attraction that it holds over the fools who cleave to it, wreaks havoc among the people. 1
Rashbam: Because it is the way of sorceresses to ply their trade in secret, and one needs to make a great effort to find and eliminate them. 2
Hadar Zekenim: If the Sanhedrin would judge her to execute her, perhaps she would save herself through witchcraft. Therefore, anyone who can kill a witch, he merited. This is why Shimon ben Shetach hung 80 witches (not through the Sanhedrin - Yerushalmi Sanhedrin 6:6).
Ramban: And the Torah tends to treat more stringently sins that causes others to stumble or that threaten them - such as a Meisis (See Devarim 13:9) and a murderer (See Bamidbar 35:31).
Rashbam: Such as the episode with the eighty witches of Ashkelon whom Shimon ben Shetach hanged (See Yerushalmi Sanhedrin 6:6).
To which form of death is a Mechashef sentenced?
Sanhedrin, 67a: He is sentenced to Sekilah
Why does the Torah refer to a sorceress and not a sorcerer?
Rashi and Ramban (in Parshas Shoftim, 17:2) 1 : Because sorcery is more common among women than among men. 2