Badass warrior with emotional problems joins heroic nature-worshipping tribal resistance to stand against encroaching evil empire, with help from astrally travelling wizards, until heroic last stand. It's not even analysis, it's a plot point in his books that there are multiple universes with the local evil empire trying to wipe out worship of the Source.
Like, the book is actually really good every time he writes it. But it's always basically the same book.