In MT Hilkhot 'aboda zara 11:4 Maimonides dealt with the definition of nihush, or reading events or natural phenomena as divine signs from God. In 11:6 Maimonides defines the qosem. Although in modern Hebrew qosem is a magician/entertainer in Biblical and rabbinical Hebrew the qosem was a diviner, a future-teller. Maimonides explains that a qosem is the person who performs certain ritual acts, enters in a trance (mishtomem) and pretend to tell the future: this is going to happen, etc. Some of these diviners, he says, use different methods for divination. Some of them use mirrors (remember Snow-white?) and some of them a crystal ball ('ashashit). Maimonides explains 11:7 that it is forbidden to perform any act of divination and it is also forbidden to go to a diviner or seek his or her advice. As it is explicitly written in the Tora in the context of idolatrous practices ( Deut. 18:10) "Let no one among you be found who sacrifices their son or daughter in the fire, who practices divination or sorcery, interprets omens or engages in witchcraft".
Divination and prediction of the future was an integral part of every pagan society. From the Greeks (the seers and oracles) to the Aztecas in ancient Mexico. The Aztecas diviners, for example, would tell the future casting maize kernels, looking into mirrors or bowls of water or tying and untying knots. As in many other pagan cultures they would also use hallucinogens (plants) to bring themselves into having "extraordinary visions of the future". In many African societies divination is still practiced today.
For Maimonides, as per More Nebukhim 2:37, all diviners are charlatans who use their powerful imaginations and persuasive personalities pretending that the future is revealed to them by an external force. For a Jew it is entirely forbidden to visit or seek the advice of any kind of diviner, psychic, card reader, etc. or whoever claims to foretell the future.