Gemara

65b (Beraisa - R. Shimon): Me'onen is one who puts semen of seven men on the eye;

Chachamim say, it is a sleight of hand (performing illusions);

R. Akiva says, it is one who 'calculates' good or bad times, e.g. today is good to embark, tomorrow is good to buy, wheat is good in Erev Shemitah...

67a (Mishnah): If a Mechashef does an act of Kishuf (witchcraft), he is liable. If he merely tricks people through slight-of-hand, he is exempt.

(Abaye): One who does an act is stoned. Slight-of-hand is forbidden, but one is exempt. One may do like R. Chanina and R. Oshiya;

Every Erev Shabbos they would use Sefer Yetzirah to create a calf, and eat it.

68a (Beraisa - R. Eliezer): I know 300 laws of planting gourds (through Kishuf). R. Akiva is the only one who ever asked me about them!

Once we were walking together, he asked me to teach him about planting gourds. I said something, and the field became full of gourds. He asked me about uprooting gourds. I said something, and they all gathered to one place.

Question: How could R. Eliezer do acts of Kishuf?!

(Mishnah): If he does an act of Kishuf, he is liable.

Answer (Beraisa): "Lo Silmad La'asos (do not learn in order to do Kishuf)", but you may learn in order to understand and give Halachic rulings.

Rishonim

Rambam (Hilchos Avodah Zarah 11:9): Sleight of hand, in which one makes people think that he did a wonder, but really, he did not. This is included in Me'onen; he is lashed.

Hagahos Maimoniyos (5*): The Gemara said that sleight of hand is exempt, i.e. totally exempt according to the one who exempts for Lav she'Ein Bo Ma'aseh, or exempt from Misah according to the one who lashes for Lav she'Ein Bo Ma'aseh. The Re'em explains like the Rambam, and says (l'Halachah) that he is exempt from Misah, but he is lashed.

Rambam (15): A witch is Chayav Misah if he did an act. For sleight of hand, in which one makes it look like he did, but really, he did not, he is lashed mid'Rabanan. It is included in the Lav of Mechashef, for which Beis Din kills, so one is not lashed mid'Oraisa for it.

Kesef Mishneh: Above, the Rambam said that one is lashed for it! Why is he lashed? Beis Din kills for this Lav! Also, why does he exempt here because Beis Din kills for this Lav? In any case he is exempt, for it is Lav she'Ein Bo Ma'aseh (there is no action)! It seems that he does an act to trick people, just not the wonder that he appears to do, so he deserves lashes for Me'onen and Mechashef. Sleight of hand is included in Me'onen (65b) and also in Mechashef (67a). He is not lashed for the Mechashef, since Beis Din kills for it. Do not say that he is not lashed for Me'onen, since it is lsb, i.e. the same Lav forbids many things - "Lo Yimatzei Becha Ma'avir Beno u'Vito ba'Esh Kosem Kesamim Me'onen u'Menachesh u'Mechashef." Another verse, "Lo Senacheshu v'Lo Se'onenu" makes each a Lav by itself. Alternatively, there are two kinds of sleight of hand. In one, he makes it seem like he does a supernatural wonder. For this he is lashed. In the other sleight of hand, he makes it seem like he does something natural, e.g. planting gourds. For this he is not lashed. Above the Rambam discussed a wonder; here he does not call it a wonder. R. Yehoshua, the Rambam's grandson, said that sleight of hand of wonders is unlike sleight of hand of witchcraft. Only one who understands these matters can understand the difference. Alternatively, one is lashed if he was warned for Me'onen, but not if he was warned for Mechashef. This is close to what I wrote (at first). Maharik (below) wrote like my second Perush.

Question (Bach DH u'Mah she'Chosav u'Medameh): If we need to exempt from lashes for Mechashef because Beis Din kills for this, we must say that he was warned. If so, he should be killed! We must say that he is not killed because he did not do an act of witchcraft. If so, this suffices to exempt from lashes!

Maharik (76, b'Sof): It seems that one is lashed for cases like the one who took a sword, cut up his camel, and banged on a board to make it get up again. This is called sleight of hand. It is a wonder to kill and revive. It is part of Lo Se'onenu. He is lashed, for through it he did an act of illusion. Perhaps the Rambam holds that the Torah is more stringent about this, lest he cause people to stray after him. This is based on the Rambam's opinion that all these matters are folly; early idolaters deceived people into following them. Sleight of hand in which he makes people think that he did something that he did not do, e.g. that he went to the place Ploni or planted gourds, but really, he did not. This is not a wonder, rather, Sheker. The Torah is not stringent to lash him, for he will not cause people to follow him. Therefore, it was put in the Lav of Kishuf, which Beis Din kills for, so there are no lashes for it. Semag considers it a Lav she'Ein Bo Ma'aseh.

Question (Beis Yosef and Bach, ibid.): What is the source to distinguish like this? The Gemara said that he is exempt, without distinction!

Bach (ibid.): The Gemara permits to create using Sefer Yetzirah, like R. Chanina and R. Oshiya. This is not sleight of hand. Semag say that the Gemara exempts, i.e. from Misah for witchcraft, and also from lashes, according to the opinion that exempts for Lav she'Ein Bo Ma'aseh. The Maharshal says that the Rambam means that he is lashed according to the opinion that lashes for Lav she'Ein Bo Ma'aseh. This is difficult. The Mishneh Torah never gives the Halachah according to opinions unlike the Halachah! I say that one sleight of hand does not use any witchcraft. This is Lo Se'onenu. Sefer ha'Mitzvos (Lav 32) explains that this is magician's tricks, e.g. through ropes in the corner of his garment. One is lashed for this. The other sleight of hand is when he uses witchcraft to make people think that he did something, but really, he did nothing. E.g. he made it seem that he harvested gourds in a field. This is included in Mechashef. He is not lashed even if he was warned for both. He is not killed for Mechashef, for he did not do an act of witchcraft, e.g. to gather gourds to another place. He is not lashed even for Me'onen, since he also transgresses Mechashef, which Beis Din kills for, so there are no lashes for it. The Rambam holds that the Beraisa of Me'onen did not exempt from lashes, for it discusses sleight of hand not through witchcraft. Semag holds that all sleight of hand is through witchcraft, therefore, one is never lashed for it.

Rosh (7:7): One who does an act is stoned. Slight-of-hand is forbidden, but one is exempt. One may do like R. Chanina and R. Oshiya.

Poskim

Shulchan Aruch (YD 179:1): We do not ask astrologers or Goralos.

Rema: This is because it says "Tamim Tihyeh Im Hash-m Elokecha". All the more so one may not ask magicians, diviners or witches.

Beis Yosef (Sof ha'Siman DH v'Chosav): The Zohar says that it is a great Isur to ask witches, even for a Choleh. Some Poskim permit using Shedim. Most who do so are harmed through this, so one who guards his soul will stay far from this.

Shach (1): The Terumas ha'Deshen says that doing an act of witchcraft, etc. is forbidden mid'Oraisa, but asking is forbidden only due to "Tamim Tihyeh." Therefore, a sick person may ask these people. The Maharshal forbids unless he is dangerously sick or if the sickness came through these means.

Shulchan Aruch (16): Sleight of hand is forbidden. One may do through Sefer Yetzirah (Rema - even to do an act).

Beis Yosef (DH Me'onen): The Tur forbids sleight of hand and also giving times for things. He holds that R. Akiva does not argue with Chachamim. He adds to them, that also this is Me'onen.

Taz (10): There are no lashes also for this, for he did not do an act. I say that the Rambam holds that he is lashed because he makes people think that he does an act. We find that one who muzzles through his voice is lashed, even though there is no action, since it causes the animal to work without eating. The Rambam holds that when it seems like he does the action, this is Me'onen. If not, it is Mechashef.

Shach (18): Hash-m put power in Kodesh names to enable Chasidim and Nevi'im to do acts that show His power. They must do so in Kedushah and Taharah, and for the sake of Kedushas Hash-m or a great Mitzvah. There is no one like this nowadays. Even Yeshayah was punished for this!

Kitzur Shulchan Aruch (166:4) and Chachmas Adam (75, cited in Pischei Teshuvah 7 and Yechaveh Da'as 3:68 DH ul'Fi): Jesters who do sleight of hand at weddings transgress a Lav mid'Oraisa, and one who tells them to do so transgresses Lifnei Iver. Anyone who can protest must do so. One may not look at it, unless the one doing it is a Nochri.

Igros Moshe (YD 4:13 DH Zehu): Surely one may not do so if he claims to do magic. One should do so only if the audience realizes that he merely moves very quickly.