In a modern occult game, the PCs might run into some new-age goofballs, or some neo-pagan eclectics, while they're looking for someone who can provide them some kind of information or real magical assistance. Chances are, those people will be useless. But sooner or later, someone is going to point them to some guy or some group that they think of as "dark", or even more often as "assholes", but that may actually have the information or skills they seek; odds are, those will be the Thelemites.
Don't get me wrong: chances are most of the Thelemites will be useless too.
Thelema is in many ways the 20th century's greatest magical tradition, born out of the Golden Dawn (which was the 19th's greatest tradition), and it was directly or semi-directly the source of so much of what we think of as Occultism today, including Wicca, most Neo-Paganism, Chaos Magick, and it was even peripherally involved in the rise of Scientology. Not to mention being a big influence on a lot of the big movers of the hippie era: Timothy Leary, William S. Burroughs, the Beatles, Led Zeppelin, David Bowie, discordianism, Robert Anton Wilson... from both the artistic and the 'philosophical' side (using that term loosely), Thelema was the well from which they all drank.
So what's the deal with it? That might be too much to express in just one blog entry, so you may need to do some extra research if you really give a damn. But putting it in brief, Thelema was a radical new expression of everything that had come before in western magick, and set up as a truly complete and coherent system of rigorous esoteric/spiritual practice for the first time in at least 1500 years in the west.
It was founded on a series of Holy Books that were received by Aleister Crowley in 1904 (at which time he had already been an ex-magician, having worked in the Golden Dawn, become disillusioned, and taken up buddhism instead), through a vision his wife had on their honeymoon while they were spending the night inside the Great Pyramid of Giza (because back then you could just do that, if you had money). The vision led him into communication with the solar-god Ra-Hoor-Khuit through a being called Aiwass, who was Crowley's own Augoeides (guiding spirit, or the reflection of his higher self, if you want to simplify it somewhat).
These workings led Crowley to re-invent the magical system already developed by the Golden Dawn into a new system, a mixture of magical practice with a new pagan-inspired (but not inherently pagan) philosophy, centered around the core teaching of the Book of the Law: "Do what thou wilt shall be the whole of the Law; Love is the law, love under will". The system was a kind of western tantra, involving the overcoming of one's self through rigorous yogic practice, ceremonial magick, meditation, and initiations.
Again, that's all the theory. In practice, what happened is that like anything else in occultism, the vast majority of people involved decided that it's a lot easier to be a poser than to be legit. Crowley was a transgressive figure, and his reputation for breaking all the rules caused him to make relatively little ground in his own lifetime; by the time he died in 1947, in spite of some initial gains, there were probably only a few dozen Thelemites in the entire world. But later, in the 1960s, Crowley's philosophy took off among the hippies and the post-hippies and later among the punks and the heavy-metal fans and the goths, so that there are now probably tens of thousands of Thelemites world-wide, and a lot more people who are peripherally connected to his work (whether they know it or not).
But most of these people were really drawn to the idea of "Do what thou wilt" just meaning "do what you like", or they were drawn to the sex-magic stuff (which was really only one small, though important, part of Thelema, and not for beginners), or to the idea that it might be "satanic" (a claim mostly made by its detractors). So just like you have a lot of neo-pagans who are really mistaking their religion for a D&D-Larp or a Ren Faire, today you have a lot of Thelemites who are really mistaking their religion for playing at being Azrael Abyss.
That is, again, one of the main things to remember in running a genuine modern-occult games. Real magical teachings are NOT hard to find, you don't need to go to old libraries and look for difficult texts for months; you can get it all on the internet these days. But its really really hard to find people who have actually worked the work, regardless of the tradition. For a lot of Thelemites, their work consists in having occasionally read some of Crowley's work, having maybe done a Banishing Ritual once or twice in their lives, maybe having joined the O.T.O. (the most popular Thelemic group) which is a bit like Freemasonry but less stable and more lame, or just hanging around wiccan/pagan groups freaking them out and telling them that they just ripped off Crowley...
It doesn't help that by definition, Thelema is one of the ultimate Individualist philosophies. "Every man and every woman is a star", says the Book of the Law; which is to say every person is unique and must find their will (their true Will, the guidance of their higher self, again really simplifying it there). This means a lot of Thelemites don't generally play well in groups. Thelemites are a crazy mix of radical lefties, total libertarians, anarchists, quasi-fascists, drop-out stoners, off-the-grid nutsos, and general whackos. As always, the ones who are really good at it, who do the work and have gotten somewhere, are often not very interested in spending a lot of time around all the other guys, or if they do they keep what they've done relatively quiet.
Even so, if you can find one of those guys, they're the ones most likely, in all the western traditions, of having something worth telling you or showing you. Ironically, for a system that says "do what thou wilt" and for a movement that is so full of people who are often about style (usually 'sinister' style) over substance, the actual PRACTICE of Thelema requires an insane amount of discipline. The payoff is that it is the most coherent magical system for systematically gaining the skills necessary for magical work. Once again, none of the teaching is secret, but the art of how to apply it in the right order is just really hard, and thus usually ignored or skipped over. It sure does bring results, if you follow through though.
Currently Smoking: Masonic Meerschaum + Image Perique