This post over in the Ars thread caught my attention.
Subject: Recalibrating Ars Magica: 01 - Power Limits
Lots of things to discuss. One of the things I've tended to notice in covenant build points. Books are really cheap, high level summa, especially, from an XP perspective are pretty darn cheap. Vis stocks are too cheap. Vis sources are too expensive. I'm not sure we want to tackle adjusting anything before play starts, but it's worth discussing before things progress or even get started.
Yeah, it kind of doesn't make sense from a "build point" point of view to get lower-level and -quality summae, when it costs just a few more points to jack it up.
I think there should just be upper limits for each resource type, based on the power level of the saga. Maybe it should take boons (purchased with corresponding hooks) to justify going over those limits.
But it's hard to asses what those should be.
I think some things were discounted in that analysis would be longevity of magi who get most of the Arts advancement from raw vis -- isolation, botches, twilight and warping.
A magus who spent his time in a high aura will gain warping. A magus who spend 2 seasons every year studying from vis in a level 10 magic aura will:
It takes 275 Warping Points to get to a score 10, after which any Twilight event is final. At an accretion rate of 3.5 Warping points per year, the ceiling would be 78 years out of apprenticehip. Most would die or go into Final Twilight before they reach 100.
That also does not take into account developpement of the longevity rituals. They were probably less effective at the time, with fewer specialists making them for those who were not good at CrCo. So many magi would simply die of old age. Even reaching the age of 100 would be exceptional, IMHO.
The highest-level books, maybe. But those books would probably be of lower quality. I can envision some old with L30 summae. But not all magi with high Arts want to, or can, spend 1-3 years writing such a book. And the quality of the vast majority of those books would be low (Q3 to Q8). Forget about any L40Q10 summae!
I would certainly agree if we said that books on Art need to be written (and copied) by Gifted individuals (including Failed Apprentices) with a Magic Theory score. Perhaps lab notes are a different matter -- they do directly not impart knowledge of magic. This would keep mundane scribe useful for magi (lab notes) but diminish the mundane scribal factories for Arts books.
As for a vis cost, it certainly is a possibility. But it has the drawback of making raw vis even more valuable, since a vis-poor covenant won't even be able to write or copy books. They'll be limited to direct one-on-one teaching
Perhaps have the vis cost proportional to the number of xp that can be gained from the book? Maybe require 1 pawn per full 20 xp to reach that level? So a L20 summae would require 10 pawns of vis to write/copy, while a lowly L5 text would cost no vis. As tractatus have no level, they don't require vis either. That would also explain why mundanes cannot copy good summae, because they cannot handle the vis required. Mundane scribes can still copy low-level summae and tractatus, since they don't require vis.
If you want that to impact the covenant build points, just say that each pawn of vis adds X bp to the cost of the book.
Just random thoughts...
This isn't correct, unless the Aura is from another realm. Hermetic magi are magically aligned, so they don't gain warping in a magic Aura, see page 168 of the main rule book.
Not even the highest level books in the Order, although that is possible. I'm starting to think that high quality books (above a quality of say 10) should be an extremely recent development. In many ways, reading through the Ars Magica books I see an Order that is stagnating. New things aren't really developed, they just refine how things are done. During a period of refinement you aren't reaching for the top, you're just trying to do what you know you can do better, safer, cheaper, faster, whatever. I'll use the US space program as my example to explain what I mean a bit better. Once NASA got to the moon, they focused on getting into orbit more cheaply through a reusable shuttle, and basically left the moon and other manned missions beyond Earth orbit. (Nevermind that Congress turned the shuttle program into a pork project dividing pieces into their districts and inflating the price.) The frontier was ignored and even forgotten and poor planning has now left the US without the ability to get people into orbit reliably. Am I alone in my understanding of the Order of 1220? I think this is why Normandy and Rhine Tribunals have the Lotharingian Tribunal to deal with, why they are so politically damaged. Why Greater Alps is gentrified...
Anyway, I'm throwing all this out there, because it shapes our perception of this saga, and I think it's important to know where people are coming from...
My bad, you are correct. 
Still, the risk of botches remain, with the associated Warping and Twilight events. I actually understated the risks. A magus with an Art at 30 that studies from vis must roll 7 botch dice. On a botch that means 6 Warping points = Twilight. That's 5.2% chance of Twilight for that single season... and it gets worse as your Art increases (Art score of 46-50 = 6.9%, 56-60 = 7.5%, 71-75 = 8.2%)
I also see a somewhat stagnating Order. And I believe that it is related to the political situation.
On the other hand, the Order was probably never as dynamic as is portrayed by those who lived it. Things have probably been made to look better than they were by those magi that survived the events. Revisionist has probably been a very popular sport.
Further thoughts on this.
It could be that writing about magic requires the use of magic (as in vis invested in the books) to really illustrate the results. You can still write about it without using vis, but the Source Quality of the resulting book is reduced by 1 for each missing pawn. But using vis in books is a relatively recent development of Hermetic Magic Theory, so old books were all of reduced quality because of this.
One thing to take into account if we say that writing and copying Arts books takes raw vis is that the magus is limited by his twice score in Magic Theory per season. That is not much of a limiting factor for writing new work, but it can become one when copying quickly. Under this, someone with a Profession: Scribe score of 2 can copy 24 levels in a single season. If this is a single high-level summa, it requires 15 pawns of vis (thus a score of 8 in Magic Theory is needed). If this is two level 12 summae, then it would only require 2x3 pawns (thus only 3 in Magic Theory is needed).
On the other hand, when copying carefully, this still makes the last season of writing (when you copy the more advance parts) difficult. Thos last 8 levels of a level 24 summa represents 164 xp, the equivalent of 8 pawns of vis (MT of 4 needed). This assumes that the spread of raw vis invested in a book progresses along with the xp represented by the additional levels added instead of being spread out evenly amongst the seasons.
Overall, I've always been less than satisfied by the book-writing process described in the main rulebook. The linear approach to writing X levels per season simply doesn't make sense to me, considering that those last levels represent so many more experience points for the reader. But that's another story entirely...
Sorry for the rambling. 
So...to have a book and pay for it...appropriately we should also be paying for the vis cost of the book, too. But as I've also said, stocks are too cheap and sources are too expensive.
So a summa L15Q15 is normally 30 bps, but the vis cost of the book is 6 pawns (105 xp/20, it makes sense for this to round up here). 6 pawns costs only 2 bps in stocks, but it costs 30 in sources. Maybe split the difference and call it another 15 build points (cost of equivalent vis source divided by two) for a final build point cost of a L15Q15 summa to be 45 build points.
What would happen with the Failed Apprentice with Magic Theory and scribe? Could he handle the vis sufficiently well to write out high level summae? Or does it require The Gift?
Libraries become valuable, inviting magi to come visit and use the library begins to make much more sense. Covenants with a great book and are vis poor may not be able to make copies for sale, because they are too vis poor, but can invite other magi to come and copy and collect some fees.
I was thinking that using only whole 20 xp might be a good idea, because it means that low-level books (up to L5) don't require vis at all. So those apprentice book are really inexpensive and could even be copied by mundanes.
I was thinking a flat cost/pawn addition would be easier to handle. Your example would be 2.5 per pawn. To avoid fractions I would suggest 3x.
So if we use both of those numbers you get the same 45 bps (30+15) for that L15 summa. And a L25Q15 summa becomes much more expensive at 88 bps (40 for Quality and Level + 3x16 pawns) as opposed to only 40 bps in the current rules.
He can still copy low-level summa (up to L5), tractatus, lab texts, etc. It's only the more advanved summae that are beyond his abilities, since handling the vis would require an undamaged Gift along with a MT score. Just like mundane scribes. In any way, the worth of a Failed Apprentice is more about helping in the lab than copying texts. But there could be some exceptions, where a specific Failed Apprentice can still handle raw vis to copy books. SG fiat.
Indeed, although I for one would have visitors pay to simply study from those books instead of allowing copies to be made. A really good book could then make up for absent sources of vis -- less reliable perhaps, as visitors vary from one year to another.
I am not sure I like the idea of writing books costing vis in addition to the time spent writing. Would this imply something inherently magical about the book which could be dispelled? Why make it more difficult to write a book, when the payoff for the author, aside from trade value, seems not that much? At least when you spend time and vis to make an enchanted item, you have a nice toy to play with when you are done. Maybe I am not understanding your reasoning; I will need to reread this thread again, when I am not so tired ...
No, it's not inherently magical and can't be dispelled. Perhaps the vis is like research materials. The original author needs the vis to confirm and demonstrate his theories. This makes sense, but I'm having trouble with copyists having a reason to use the vis.
As far as the payoff for the author, that doesn't change by increasing the cost. The increase is felt by all book writers.
Well, I was seeing it as a way to explain 2 things: why better books should be more expensive to obtain, and why there are no mundane scribe factories in Mythic Europe.
As JL mentioned, there is little point right now in purchasing lower-level (or low-quality) summae, since the cost scale is linear (bps=L+Q) whereas their usefulness is geometric (pyramidal xp). Maybe a simpler way to handle this would be to just change the cost of books.
Are we going to go with "vis required to write books"?
If the goal is to make high-level summae more expensive, here's a different proposal for simply change the build points required to purchase summae.
Ability summa = Level * Level + Quality
Arts summa = (Level * Level + Quality)/5
This makes the low-level summae less valuable than under current formulas. The tipping point comes at Level 10 for Arts and Level 1 for Abilities, after which books are more expensive than currently. A L15Q10 Art summa would cost 47 bps (instead of 25), L25Q10 becomes very expensive at 127 (instead of 35). Meanwhile, a L5Q10 Ability summa would cost 35 bps (instead of 15), while a L10Q10 rises to 110 (instead of 20).
Under those formulas, the bps per xp contained by a book tapers at about 0.4 -- currently that ratio keeps getting lower as the level rises (0.4 at L9, 0.2 at L15 and 0.15 at L20). This comparatively brings tractatus to a more interesting ratio of 1 bps/xp.
If we want to restrict the copying of magical texts to mundane, we can simply house-rule it. Require the Gift (whole or damaged). Or saying that higher-level summae require a higher score in Magic Theory. Or both.
Thoughts anyone? Aside from JL and I, only Archimedes commented at all on this topic...
Adjusting the build point cost is probably a more reasonable alternative than employing vis costs. However, that only addresses the build point cost of the books, but it doesn't address the transactional costs of the books once in play. Books can still be quite easy to write and copy.
That's what I've been thinking about.
... and I'm still not sure I like the idea. Changing the build point cost is more palatable that requiring vis, but I guess I don't see the RAW as broken on this matter in the first place, so I'm not sure the rules tinkering is necessary ...
High level summae are too cheap. Why is it possible to make a L15Q15 (Arts) book? It only costs 30 build points, but it gives 120 xp, assuming a score of 0. Comparably 3 Q10 tractatus cost 30 bp and grant 30 xp. Which one is a better value? The value proposition changes as someone's Art score increases, but it has to be 14 or more. A score of 13, at the minimum XP level for a score of 13 needs 29 xp to get to 15th level. They can get there in two seasons from the summa, or 3 seasons from the tractatus, losing only 1 xp in the process.
I want to revisit my aura modification suggestion again. But this time viewing it through the lens of this saga being relatively low powered.
Progressing the Aura strength where the bonuses to the die rolls mimic the progression of Arts, meaning an Aura 1 adds +1 and an Aura 10 adds +55 in a friendly aligned aura might seem, at first blush overpowering. It doesn't, however, change for lab totals, the aura "score" adds to the lab total, and the aura "xp" adds to spell casting totals, or subtract if the aura is not friendly. This seems overpowering, but when you get into foreign auras things change drastically. Magi, unless they are extremely powerful or use low level spells will have great difficulty working magic in a typical city. A divine Aura of 3 translates to a adjustment of 6 to the die roll. If it's a hermetic magus doing something in a divine aura they get a -18 (3x6) to their CS...
Such a change mimics the order we have to date. Magi confined to their places of power. A few reside in cities, those who are comfortable doing so because of the Gentle Gift, those who live in a lacuna, and/or those who have sufficiently studied magic to their desired level. Many spells which make living comfortable are relatively low level, so casting them in a typical city is still possible, but will likely fatigue the caster...
I think this is extreme, but I can live with it if you really want to do this. It's just that such a penalty is so much worse for young magi than the more advanced ones.
It dramatically changes the balance of power. A just out-of-gauntlet magus won't be able to do any magic in a level 4 Divine aura (-30 to CS). I think the penalty scales up too quickly for the Divine. This, to me, encourages young magi to simply shut themselves in their lab instead of going out on stories, particularly where mundanes are concerned.
Note that it also weakens the Aegis as a protection from magical attacks (the aura bonus adds to Penetration, but not to the protection of the Aegis).
Where does a Divine Aura 4 exist? Closer to a church. If one is in an area where there are a couple of churches in close proximity you might see an aura of 6. Beyond the penalty, however, I think you're discounting the risk of a botch. I'd be very concerned about casting a spell in a Divine Aura just from that risk alone, but I'm botch averse. A holy magus probably isn't interested in doing magic near a church, either. It also makes it a stark divide between God and personal power...
IMO, It's almost trivial to defeat an Aegis, anyway. Just collect an AC. That being said it also allows for casting a more powerful Aegis. A couple of magi work together in the lab so that one of them can learn the 10th magnitude Aegis. The Aegis, IMO isn't there for the magi so much as it is there for the covenfolk. Magi don't want to have to go out and deal with anklebiters all the time. Sure, if there's a big bad enemy, they'll get involved. My suggestion doesn't change the equation. Magi do receive some protection, but layered with Parma, they are going to be well protected.
Going hand in hand, I think the quantity and qualities of auras need to be diminished. Durenmar's 7th magnitude Aura is something to marvel at. Any auras that are greater than that are likely rather small, such as an Aura 9 being the size of a Size -2 lab or something? And Aura 10 being Size -4...
Oh, and I like the idea of magi generally staying safe within their areas of power. Young magi are going to be risk averse and are going to rely on subordinates to handle mundane things like cities. And they are going to be frightfully scared of magi who work magic in cities or other non-friendly auras.
The countryside is going to have an aura of 0...
Agreed, high level Summae are too cheap.
But mainly in build points, which makes the level*level version nice.
The problem (IME) is rather less pronounced in-game (where build points are irrelevant).
Making books more expensive via adding a vis cost is... not the right direction I feel, especially given how cheap Vis stocks are (that's how you'd pay for the Vis with build points, yes?) vs how expensive Vis sources are (this should affect in-game purchaces more).
Did that even make sense?
+1
If it's the build points we are worried about, let's put a limit on summa levels or use the a modified build-point formula. I would still prefer not to mess with the rules for writing summae.