I am thinking about starting a 4th edition campaign in the Stonehenge Tribunal, but I am having a hard time coming up with info on House ex Miscellania.
I have enough cash to buy one book; Should it be "Houses of Hermes" or "Hedge Magic"? 
For 4th ed?
Do you already own "Heirs to Merlin"?
There is no 4th ed. Houses of Hermes, only a 2nd ed. and a 3.5 ed. (a re-issue of the first when Wizards owned the line). Which addition are you talking about.
I like the 4th ed. Hedge Magic quite a bit, but don't recall how well they'd work for Ex Miscellanea. Of course, it would give you ideas.
There is a lot of information in the 5th ed. Societates about Ex Mis. (naturally). I suppose you could backward import it to 4th ed. if you wanted to.
Interesting question. Thanks,
Matt Ryan
Yes, I do allready own "Heirs to Merlin". All it says is "The Domus Majore of House Ex Miscellanea is located in this tribunal". What a big load of help that was. 
btw...
there is a listing for a 4th edition "Houses of Hermes" here:
Very generally, House ex Miscelleanea is a lot like a Political Activist group. Lots of individuals and smaller groups with something in common, coming together to achieve what they couldn't individually.
And the thing they have in common is... that they don't fit in anywhere else.
If you were a hedge-mage that did maple-syrup-magic (whatever that might be), then when the Order comes knocking with an offer you can't refuse, you join House EM. If, 200 years ago, your Parens' Parens' Parens' did that, then there might be a half-dozen mapley-syrup-magic ex Misc magi wandering around the Order, a tradition within ex Misc. Cool. Or not, either way.
Beyond that, it has all the flaws that you can imagine such a coalition to suffer from, "disorganized" perhaps jumping foremost to mind. Barring specifics from canon, that should be enough to get most imaginations started.
That is the 3.5 version, re-issued by Wizards before Atlas developed the 4th edition rules. Not that it would be a problem; I don't remember many mechanics in the book that would need to be imported.
I'd say, then, that this would sever you better than Hedge Magic if you are focusing on Ex Miscellanea. However, I don't remember that any particular House got more than a page or two write up, and you might be disappointed by the lack of specific Ex Mis info this might contain.
cheers,
Matt Ryan
tyvm
I'd say that Houses of Hermes: Societates is the most comprehensive source of information about ex Miscelleanea. It is for 5th edition, though, so you would have to make some adaptations if you want to use the rules...
As I recall they are close enough that I don't think a backward port would not be a problem, here. I don't have HoH 3.5 (I have the older one and the three replacements). I do have HM. HM is good...but the writer of Ex Misc in Societates had read it too, you know? THere are good bits in it, which I hope will be in A&A that are not in HoH:S, but basically HoH:S gives you heaps more polticial detail ,and a lot more different little traditions for members to be in.
The only reason I haven't bought Societas is because its not yet available as a PDF.
I've printed each chapter off the other two HoH books and spiral bound them as individual splat books; it makes it easier rather than having players share a book between them.
But yeah I'm missing the information on Ex Misc myself as my saga is set in Loch Leglean. My creating a Ex Misc almost always results in me making them a covert Diedne. Not because its obvious but because it's the easiest route.
I'd appreciate the assistance in creating a greater variation of Ex Misc myself.
That said I think that the 5th edition is superior to the fourth in every regard. Although character gen is taking longer than I remember for 4th but I reckon that's just a familiarity thing.
The prevalence of ex-miscelanea is possibly the greatest obstruction to playing in the Stonehenge tribunal. I have always found despite many great efforts any and all attempts to incoprporate 'hedge wizards' into the system have been quite ropey.
As a result all my campaigns have been based on the principle that a bunch of devoutly hermetic wizards from various more traditional houses have formed a new covenant in the tribunal; dealings with that rag-tag bunch has been at a distance.
Like many other campaigns ex-miscelanea seemed to feel a lot more like diedne than the brutalised non-hermetics fored to pay alliegence to a magical tradition they have no real understanding of which we should expect to find.
It's not much but it should say more - there's an entry on Cad Gadu including a bit on the leader of the House.
Other than that, if you want something on the Miscellanea few things can be as recommended as the Houses of Hermes: Societas.
It depends.
Both of those are 4th Edition titles; I think the 5th Edition equivalents are much better. But if you're playing 4th, then Hedge Magic will probably offer you more for specifically Ex Misc. wizards.
If you're playing 5th Edition, then I would suggest you consider Houses of Hermes: Societates. It goes a lot into the history of House Ex Misc, and more importantly has rules for making up your own supernatural powers for Ex Misc traditions.
As a self confessed Ex Misc and hedgie tragic from way abck I strongly suggest you look at HoH:Societas - not only does it have several pre-potted tarditions with unique abilities but has several other sketched out traditions, guidelines for developing that ever defining Major Supernatural Virtue and a host of other good ideas.
As for ArM4 Hedge Magic, I suspect some of it will be replaced by ArM5 Art & Academe but I suspect Mark and Ryan are bound by NDA. I'd wait for the Januray release of this if you can.
The old Houses of Hermes doesn't really cover anything that is not re-envisioned in ArM5 HoH:Societas.
RoP:Infernal is also useful fro playing Thessalian witches and other summoner types...