You tell me. Nailing the library was hard enough. 
That's why I figured the "flexi-sources" might be worth a try. We've been trying to determine in advance what we'll need and how much. IMHO, it is much more logical and make for better storytelling -- sources are discovered, dry up and change over the course of a saga.
I think I was the only one to complain:
You have my blessings.
NB! My home table rules that the Aegis does not need to penetrate, so I had not even considered that.
Actually, I could easily change on of Titus' spells to a level 30 (D: Sun) Wizard's Communion*, instead of Feeding the Font of the Covenant.
In many ways, this would even be surperior, because then I can invent Feeding the Font of the Covenant and use experimentation to do so, hopefully achieving a discovery for my break through.
Unless someone protests, I think I will do just that. It will add 20 levels to our communion.
*Known locally as the Ritual Communion, to avoid the complication of multiple spells with the same name.
I will update the wiki to reflect this.
Does everyone feel that we will have enough Vim sources?
Personally I think Petronius will be fine with 2 pawns/year of Vim on average over the course of the saga. His Mercurian Magic also means that the Aegis will cost less, because of the House Rule that allows the vis saving of Mercurian Magic even when non-Mercurian participate through Wizard's Communion.
I also see him needing 2 pawns/year of Rego, 1 pawn/year of Terram and an equivalent of 2 pawns/year of various other Arts. For a total of 7 pawns/year. Having purchased 12 pawns/year with my build points, I think my magus is adequately covered.
It might be a good idea for each of you to post what your expected vis consumption is. I encourage you to do so, but that is certainly optional and volountary. 
BTW, let's remember how resources will be allocated. According to the draft charter currently on the wiki:
So at saga start, we will probably have a small vis stipend from the covenant, for there will be little stores to prepare for emergencies. Exactly what constitutes "sufficient stores" for each Art. But once those stores are accumulated, we will probably receive most of the vis collected. At 39 pawns/year, my expectation is that we will split at least 25-30 pawns (so 6-7 pawns per magus).
Does that seem reasonable to everyone? That will be in addition to any vis collected in stories or through trade (for services, items, etc.)
That would work well. 
Even if Aedituus knows a regular version of Wizard's Communion, we will have lab texts for level 20 and 30 version of Ritual Communion, so it will be easy for him to learn it. This might even be better, in a way, for it would give us another version of the spell in the library (though at the price of 1 year with a weaker Aegis). 
Good suggestion. I will add the variant's spell name and description on the wiki, and adjust the spell list for Petronius.
I honestly have no idea.
Fo one, it depends heavily on whether I manage to Initiate Hermetic Architecture or not, as well as how many odd Vim-based devices I can dream up.
I did have the thought though, that a T: Structure version of Feeding the Font of the Covenant be enough to affect the aura at the secondary site, which is an idea Titus might well take further, in the name of research.
Unless ofcourse his sodalis complains, in which case he'll have to find another aura for those test-runs
This gives me a nice problem though, as Titus has short-ranges magic
Time to work a bit for casting that!
It should be easy to find another, less-valuable, aura in the forest. It is sprinkled with small, level 1 magical auras. No need to risk the covenant's vis sources to experiment with his spells.
Ah, but it needs a structure
Have some grogs carry timber, stones, etc. and Praxiteles can probably build it...
Excellent, fine with me
Or even have the covenfolk build something for you. We have both a carpenter and a stonemason listed in the covenant's specialists, so a basic hut can quickly be built is needed.
The Hermes Portal Petronius is bringing with him is above 40th level, which is the suggested level limit for lab texts. Are we all OK with it? I don't see acquiring this later on to be a problem. I've established some nexus with Bibracte, and I have NPCs there who have/know the spell, and House Mercere doesn't really keep this lab text a secret, unlike the method for creating Mercere Portals...
I forgot about that limit. And initially this was a lab text from personal build points. I swapped it later on to the shared build points because it made accounting easier, and to leave some of the more exotic healing rituals as private (with the idea that these would come from Octavius).
My rationale for Hermes Portal was that, as a Bonisagus who specialized in portals and spent some seasons at Durenmar, Petronius would have had access to this lab text and gotten permission to copy it. As you say, the spell is not any kind of secret (it's rather famous), so I never imagined access to it would be restricted.
I will bow to the troupe, however. Petronius will get a copy at some point -- just figured that since he has Driving Goal (major), this would have been the first lab text he'd get a copy of, no matter the price, while rationalizing that this would be useful to the covenant. 
Well, I don't personally have a problem with it (in fact, quite the opposite), but I thought it deserved commentary, given my opposition to that other thing/spell It's a full disclosure thing.
Agreed and understood. I just thought I'd explain the rationale behind the choice.
I even refered to that limit above.
No, I'm fine with that.
Besides, how could house Mercere hope to keep it secret? It's not mentioned to be their secret to keep.
Guernicus was a Terram magus - might easily have been his secret.
After all, Mercere wasn't strongly associated with travel before the loss of his Gift as I recall.
I'll be posting my build points later tonight or first thing in the morning.
I'm almost done with them.
Just a note that I've changed the display format of Petronius' build points on the wiki to use a table.
I did not change anything to the allocation of his build points. 
It's an experiment to see if it makes it easier to see what he purchased. It's got that advantage that the table is sortable. If we use the same table for all of the players, this would eliminate the duplication between the first section (by player) and the second (overall), avoiding potential discrepencies. The sortable columns would mean that we can have the information presented in any number of ways.
Let me know what you think of it. 
The concept for the additional Vim vis source at the secondary site:
Dog Roses of the Burned Tower
At the secondary site, bushes of dog roses grow up at the base of the burned tower. Those bushes gather and concentrate magical essence into their fruits (rose hips). They become particularly potent in the winter, after the first snowfall. Once collected and dried, they contain Vim vis (it takes a large handfull of the best rose hips to form one pawn).
5 pawns of Vim vis, harvested once a year in winter