A young mineworker with considerable magical powers, yearning for a better life, manages to gain an apprenticeship with a dark group of wizards, and soon learns that finding personal happiness entails as many deadly perils as choosing sides in the struggles between power-hungry factions.

"finding personal happiness" is too abstract and not an "exploitable commercial element". It should be in the theme rather than in the logline.

Well, things have changed a lot since I originally wrote it. But I think you'll get the idea if you want to read the first 3 chapters (I can send you more, if you want):

http://jefferycotton.com/first-chapters-from-war-of-the-unwanted/war-of-the-unwanted/

Agreed - "sect" is a better word. And I'm with you again - while it's good, it gives up too much (doesn't leave anything to the imagination).

Question: does the MC have the ability to alter the outcome? Is that ability directly related to his magic powers? Or simply the impact of his decision to join one sect or the other?

If you want to share your 30-pager with me, then that could help me wrap my arms around this one.