I'm setting up a magus focusing on wild nature, but I wanted to run this past the boards here. 
What kind of magical focus could he have? Would "wild nature" be a Major Magical Focus, or is it too big for even that virtue. With wild nature, I mean wild animals, wild growing plants, wild rivers where no one travels etc.
What do you guys think?
E.
Hmm I was toying with something similar for my character still under creation. Wild Nature or "Wilderness" would likely cover An, Aq, He & Te (and all the techniques) but be confined to only those things neither processed by human industry nor domesticated for human use. This would cut out the bonus for affecting ANYTHING in any population centres, any clothing or tools.
For balance sake it should also have NO bearing upon Au, Co, Ig, Im, Me or Vi spells or effects.
This does, arguably still leave a pretty wide range of possibilities. One way to limit it further would be to focus on Natural Cycles of Growth and Decay in the Wilderness thus reducing the Technique range to Cr & Pe.
Whatever the consensus, it would have to be a Major Focus.
Too wide IMO.
It affects 99% of the predators of the world, all growing trees that do not pertain to orchards/stand in adivnene aura, all the major rivers of the world.... All mountain ranges (anyone that tells me that a Boundary spell to affect the Alps cannot use this focus would have serious problems showing me the alps are "tame") etc etc.
I would not allow it. Unless you refer to only magical sites where things are really wild: like wild places with a magical aura of 4+. The rest of the forest/wilderness would not be wild enough to justify you having a bonus.
Xavi
Unless of course you are playing in Ireland, Scotland or the Novgorod Tribunal. 
Well, if the forest has a magical aura strong enough, sure.
Still too wide. Has flavor but can be abused freely for me to consider it widely. A sensibility to auras (your mage doubles the aura interaction chart modifiers, for example) as a minor virtue/flaw would have the same effect when it comes to flavor (great in wilderbness, sucks in settlements) and be much more balanced.
Cheers,
Xavi
Hmm, very intriguing idea Xavi, wonder why I didn't think of Aura interaction. What would you think about an mmf in Aura Interaction or "Auras"? Would such a thing be possible and if so what sort of mechanics might one apply to it.
Dunno. That was from the top of my head.
"Aura sensitivity" or another name like that, doubling the bonuses/maluses of auras might be an option, but only in wild places. So not in the covenant 
If you want to have your lab with a massive aura, make sure you have a -3 lab, otherwise it would be too ordered (human) to apply the bonus of wilderness.
The later would be to prevent abuse like searching for a +7 aura to get a +14 bonus to lab totals easily. The lab limit would reduce the bonus to (+7 - 3) *2 = +8. Hefty, but not overkill
Going into a settlement with a +3 aura can be a pain in the ass for this magus.
Minor virtue. It needs refinement for sure (all that is from the top of my head, at work) but the idea would be along those lines. Pretty much to being susceptible to the divine the infernal, faerie AND magic auras. Maybe doubling botch dice in non magical auras can be fun as well. If you want to play big in the wilderness go for it, but you should be sure to be careful in non magical environments
Xavi