Champions of Mystery provides a wealth of options for players and GMs who want to explore more options for magic users - 11 subclasses, new feats, and a ton of lore to expand what you know about magic in your world (including new factions and NPCs). Very well written and clearly extensively playtested. I'm interested to see how the "living document" method of releasing things works. This is well worth the asking price.
[5 of 5 Stars!]