From publisher blurb:
The mystic is an initiate of an inner mystery tradition that seeks direct communion with the multiverse in order to achieve enlightenment. Insight, awareness, and a deep connection with ultimate reality are the hallmarks and ultimate goals of the mystic.
Do you need a stand-alone mystic class for your Old School game? Are you playing a mystic and want a quick reference book for the table without having to flip through the entire Players Manual? Curious about Adventures Dark and Deep and want to take a look without diving in all the way? Here's your chance.
The Mystic is a complete player class suitable for use with any old-school game. It's an extract from the Adventures Dark and Deep Players Manual, and contains the class description plus all the spells available to the mystic class (including a ton of new spells unique to the class).
If you already own the Adventures Dark and Deep Players Manual, you don't technically need this pdf. But it can be pretty handy to have a quick reference guide that gives all the essentials in one place.