Magick: Liber ABA, Aleister Crowley

Crowley’s masterpiece. If you haven’t been exposed to Crowley before (outside of his image), you’ll be shocked at the clarity of his insight and wit, along with the range of his technical knowledge. Crowley’s system took the Golden Dawn material, added in Eastern mysticism and sex magick, and ratcheted the whole thing up to the tenth power. Don't get lost in Crowley's personality or often-disturbing biography—what's important is the techniques. Alongside this, you’ll likely want a copy of the equally important Gems From the Equinox.