I think this is the first Kage Baker novel I've read whose jacket description properly captures its feel (though the description for The Anvil of the World comes close). The first paragraph (and the first section of the second paragraph) sound exactly like at least half of the heroic fantasy novels being written today, and in broad strokes, this novel follows that very popular story arc. But throughout the story, and coming to the fore at the end, is the sort of wry humanism that is so at odds with most of heroic fantasy, and so trademark to Kage Baker's (and Connie Willis' and Lois McMaster Bujold's) style.
This is the story of how the Master of the Mountain and the Green Saint came to be who they were in The Anvil of the World, making it a prequel of sorts, though both books stand equally well on their own. As in The Anvil of the World, Baker doesn't confine herself to even-length chapters, nor does she stick with one viewpoint; some sections are first-person narrative, one is second-person, and one is third-person with a first-person frame -- though while it isn't always clear who is speaking at first (because they are characters that haven't been introduced yet) Baker is always in control, and the reader is immediately aware that the perspective has shifted and where in the world it has shifted to.
Most of the story revolves around Gard, who will become the Master of the Mountain; the Green Saint isn't born until halfway through the book. Gard is a wonderful character -- despite all the baggage handed him by heroic fantasy convention, he retains a wonderful clarity of purpose: all he wants is the chance to live and be happy, and he will do what seems necessary to make that as likely as possible. He encounters several mentor figures (another fantasy trope) including Balnshik, who we met in The Anvil of the World; he attracts a ragtag bunch of followers, outcasts in the world at large, through his strength of character; and he forges himself (with the help of those mentioned above) into the sort of tool so very common in heroic fantasy: impossibly skilled at everything he sets his hand to, be it conventional fighting (with any weapon) or magic.
But just as his journey appears to be veering too far into teen boy wish-fulfillment, Baker grounds it yet again in his simple desire for happiness. He bests his enemies not to make the world a better place, but simply to get himself and those he loves out of harms way; that accomplished, he takes whatever jobs come to hand (I particularly enjoyed his turn as an actor) to keep food on the table and a roof over his head. If I have one quibble, it's that the Green Saint was not given as much depth as Gard, and their romance was of the "love at first sight" variety. But while that quibble was strong enough that I couldn't love this volume quite as much as The Anvil of the World, The House of the Stag is still one of the best heroic fantasy novels I've read in a long time.
