Hmm, the amount of stuff I’m considering homebrewing is far less than what’s presented in any of the stocks. I mean just cause there’s a big set of lifepaths for dwarves and you can play a dwarf doesn’t mean the game is “all about dwarves.”
Doesn’t the same logic apply to Witchers?
If it’s built into the game it’s neutral at your table. Anything you homebrew is obviously emphasized because you, the GM, have already signaled greater interest in it.
More importantly, Dwarves can do all kinds of things. You can have a valiant warrior, a skilled crafter, a disgraced drunkard, a miner, an administrator, a wanderer. The same is true of humans. There are very, very few cases where you need one specific lifepath to do a kind of thing, much less a series of them. Or compare it to soldiers. There are many soldiers lifepaths—there’s a whole setting of them!—but you don’t need any particular one, or set of them, to be a warrior. You can be a squire instead. You can be a bandit. You can be a guard. You can spend general points. And there are so many different ways of soldiering. Infantry and cavalry aren’t the same, officers and grunts aren’t the same, and the vanguard and the supporting personnel aren’t the same.
Witchers, I’d argue, are too much the same, and there is no alternative way to do or be that thing. They have mutations, use swords and signs against monsters, and have the ability to use and often make potions. A witcher is just one kind of thing. In BW, that gets at most a training LP and a “doing it” LP, and frequently the training gives multiple options of mastery LP. Just not different schools, entirely different things that you are trained to do.
Those themes you mentioned are awesome, and I bet your players won’t have too much trouble making awesome stuff to fit them, even in the standard LPs. Probably stuff you’d never even think of. Me, I’d hesitate to put together a concept-specific lifepath merely because I’d rather see what the players come up with on their own.
That’s a great point. I’m more familiar with the source material compared to my group so maybe that gives me tunnel vision. Who knows what they could come up with? After all, maybe there are Witchers who don’t use Signs and instead get possessed by the spirits of ancient warriors? Who am I to say no to that?
A couple years back, I played in a campaign where the pitch was that we would all be witchers (you saw the recruiting thread on these forums). None of us actually ended up playing witchers.
Quickleaf, I wonder what kind of game you’d get if you just pitched “We’re a group of monster hunters with an infamous reputation and an affiliation with the Hunter Guild.”
That doesn’t even have to be the pitch. There’s room for that character alongside wizards and nobles and elven rebel-terrorists.
Bingo! 
I was reading this thread, and it seems that most people commenting are pretty wary of the whole Witcher Sub-Setting idea. I get that hesitation. It’s definitely a lot to try and work up, and if you are newer to the game you definitely want to make sure you have a handle on the basics before diving into homebrewing. My group bit off way more than we could chew, when first learning BW, and it turned out to be very overwhelming and difficult; however, it is a testament to how great the game is that even though we approached it terribly in the beginning we still fell in love with it. That being said, if you do feel like you have a handle on the basics then, I think a Witcher Sub-Setting it very doable.
While Wayfarer is absolutely right about the core stocks not having paths that are so linear and locked in, it is worth mentioning that the Great Wolves in the MB are very much made to be locked into very specific paths. Also the Paths of Spite variant for elves, on the wiki, http://www.burningwheel.org/wiki/images/1/13/Path_of_Spite.pdf, is a great example of a Sub-Setting that has a more stock/LP mix. If you’re going to do something like that; however, it should have lots of limitations. Once in, a PC should be locked in, unless they want to take major negative consequences. Also, for the traits the meaty ones shouldn’t be required. The really beneficial traits should require the player to invest extra trait points. I worked up a Witcher Sub-Setting. I don’t know much about Witcher, just what I picked up from some research online, but I took a stab at it. I made it so there are different paths of specialization, so if multiple players want to play a Witcher, they can do so without being clones of each other. Also, it still completely possible to make a Witcher, with all the perks. It would just be a 6 lifepath character, which would be out of the scope of most BW games. I set up Signs like elven spell-songs. They each would take 2 points to open. I didn’t specifically flesh them out, but you could look at the elven spell songs for ideas on how to do that. Potion brewing would also function like a spell-song. It would be a very simplified limited version of enchanting, which only makes potions. I forgot to mark it as an ability that costs 2, but it should.
So here’s the link: https://docs.google.com/document/d/1JoV8rwnLZQGrma_F89GIrmQJ9b1gmTh7GhCyvwJBcnc/edit?usp=sharing
I’ve never used google docs before, so let me know if the link doesn’t work.
From this quote alone, it sounds like you want the Witchers to have an emotional attribute like the Elf’s Sorrow, or the Orc’s anger. It would give them 1) a limited set of supernatural abilities, 2) a forkable skill that makes them more potent in critical scenes, and 3) it makes their mutant-ness crucial to who they are as a character. This emotional attribute will continually level up, causing the Witcher to continually confront his own tortured spirit, creating drama (yay!). Also, it means there are consequences. When it reaches exponent 10, hes done- maybe he just walks up to a monster and refuses to fight, or maybe he becomes one himself. Doesn’t seem overpowered to me if done right.
I don’t know. Witchers aren’t really fueled by their alienation, and it’s more an emergent property of the racism and xenophobia of the setting than something built into being a Witcher. The games hammer home Geralt’s position as an outsider; the books do not, and in fact he seems considered entirely a (mutant) human.
Feeling like an outsider, defending humanity from monsters but not truly a part of humanity, is great Belief fodder. I’m not so sure it’s an ideal emotional attribute.