Anyone have good rules of thumb or formulas they use when determining art, magic theory, penetration, finesse, concentration, etc scores for NPC magi past apprenticeship?
Obvious you can use the character creation rules and do it rigorously, but how about on the fly or with minimal preparation?
I'd use the maximum score by age guidelines from character creation to determine their scores in what they are best at, and then stagger downward from there.
For instance, an 80 year old Ignem-specialist hoplite who is 60 years out of apprenticeship might have an Ignem 25 and a Penetration 9. His other arts could be in the 5-10 range and his abilities between 5 (for those he's pretty good at) and 3 (for stuff he's dabbled in).
That's my quick and dirty estimate, born out by a couple of old magi I've actually creating using the detailed character creation rules.
I use magi given as examples in the books. I look for someone about this age and redistribute the art and ability scores given. So to create an old Herbam specialist I take Phillipous Niger (GotF) as a template and change Perdo into Herbam, etc. etc.
Works quite well for quick character creation on the fly.
However, major NPC are done by the 30XP/Year rule, which results in deeper characters.
This seems like a really good way to go. However, once characters are more than a few years past gauntlet, the 30 spell levels per year is unrealistically low and it becomes less and less believable as the character ages. If the provided characters don't use the option presented on the right hand column of page 32 they will end up being too weak to believably represent the product of the advancement rules. I'm not certain that Philipus and the other magi don't fit this description.
Just thinking off the top of my head perhaps 30 xp per year or 30+(years since gauntlet /2) spell levels might be a reasonable representation.
If th NPC magus is not throwing around spells much or anything, just fudge some numbers as you go. If the NPC is going to be an important part of the saga, stat him out the slow way.
I have found the 30/year is reasonable for XP except where spell levels are concerned.
A mage could easily add 40-80 or more levels in spells in a year in their specialty art once they start to get advanced (create a level 10 in a season easily, level 15 is not hard to believe, level 20 in season for advanced mage and that is for inventing. Learning from books can be 80-120 or more spell levels in a year easily (lab total 30 means level 30 spell learned).
(let's see: Int 2 + MT 6 + aura 3 + best tech 8-10, best art 13-15 = 31 or level 15 spell in season, level 20 in 2. Older mages can do even better and that is not counting things like lab specializations, higher auras, similiar spell bonuses, virtues (inventive genius), experimentation, etc)
In general, I would either copy an existing example from a book swapping around arts for appropriate specialization and changing spells for spells of same level or age manually with a penalty to yearly experience for every seaon in the lab (basically 4 season in lab is 8 xp(4x 2 exposure), 4 seasons otherwise is 30 xp so -5 1/2 xp per season in lab.
This gives the yearly totals as follows:
1 season in lab: 24 xp + result of labwork (2xp must relate to labwork)
2 seasons in lab: 19 xp + result of labwork (4 xp must relate to labwork)
3 seasons in lab: 13 xp + result of labwork (6 xp must relate to labwork)
All year in lab: 8 xp + result of labwork (8 xp must relate to labwork)
It is worse than that. My two-year past gauntlet magus, Roberto of Flambeau; he can invent any spell level 20 or lower in a single season from Lab Text, or as high as 40 if it happens to be Creo Ignem (Aura 6, Magic Theory 4 (spells), Int +2, and a +7 lab specialization for spells). I think a more accurate estimate would be 80 levels a year for young magi, 120 a year for mature magi, and 160 or more for elder magi.
I like the format of the formula in the book, but I change the numbers. I now use 40/year - 8/(lab season in the year). This produces much more reasonable numbers. (I was able to make a good case for this and successfully defend it on the mailing list. And that was before I found out how to get Q32 Art tractatus with cheesiness, Q23 just with real focus. Not that that ever actually factored into the argument.) Then I'll add some points for things like Book Learner, based on an estimated frequency, like saying it will apply once per year on average. I prefer doing the spells and items based on the lab total.
Chris
I like to decide how "bad ass" I want the magus to be and take one or more of the PCs as a template and adjust from there. So if this guy is twice or half the Terram master as the PC Terram master, take the best PC Terram score and multiply by whatever. If the monster is supposed to be easy or tough then I take average penetration or combat and add or subract X. This way I can specifically tailor the NPC to the group.
There is where I differ, and my method has pros and cons. I design NPC's as indipenand individuals, without reference to the player characters in the group whatsoever. Customized encounters don't work for me. If they eat him, I made it to easy. If he kills the PC's, I made it to hard. Designing an NPC without such considerations allows me to remain neutral and impartial.
While I agree that making a totally separate character does remove one from the role of "mean GM", after all the crit is made by the rules, I don't think it makes me any more neutral as I find that I tend to be more ...possessive of a character I wrote up than of a character generated from the PCs stats. If I have to think too much about what a character did three summers ago in the lab, or whatever, then I've put something of myself into it and that makes it almost as if it's a group against me scenario, not a story. That, and I tend to spend all my time trying to geek out a couple of extra points out of the rules for character stats rather than come up with a good character. Perhaps that's my own character flaw, and I don't mean to project it on anybody else. I just find it easier for me to remain neutral since if the group can't take on an npc calibrated to be x% of them then it's play style, not numbers.
If he is a villain, I'll find a way to reuse him. Slap a coat of paint on him and a new name, or just save him for some other game in some other saga. Many NPCs are more like associates or rivals though, and they will have a long life of useability. I suppose that, since I generate so many different characters just for fun, I don't get that same posessive attachment. I do notice myself hitting similar design patterns again and again though (I focus mainly on spells and abilities, not so much on enchantments or familiars).
My main issue is that I don't like the "omnipotent elder" NPC in the slightest. You know, that character who gives the players missions and allows the SG to act haughty and boss junior magi around. The covenant elder, a local archmagus, someone's mentor, etceteras. This is the guy you slap arbitrary high scores on or simply say "don't bother rolling, he wins". Any character has a chance of successfully defying or defeating any other character, no matter how great their difference in power levels, even if that chance is miniscule, it is still there. Everyone has a weakness.
But alas, I am also inconsistant. I do use the slapped together NPC on occassion using arbitrary scores. Never for a villain, but for an elder magus the players will only meet once or twice. In fact, I may not even stat him out, just make character notes.
I'll bite, it seems to me that the core book rules max out at 14 (good teacher and +5 com)
The present errata page doesn't seem to have any adjustments to the covenants rules so I think that you max out there at 14. That is + 5 comunication + 3 good teacher + 1 scribe + 1 illuminater +1 book binder + 3 resonances or +1 resonance and + 2 for placement in floregium.
The book can't have it's quality increased by glossing by anyone with a communication of less than +6
A commentary gets an additional +1 but it isn't a tractatus and thus can't be included in a floregium.
What am I missing?
Right, I was just referring to tractatus, not to commentaries.
First, do remember I spoke of cheese. But I did goof; I forgot a difference in application between two (major vs. minor) virtues. My maximum is 26, but I can do it with only Com +5 and 2 points of virtues instead of Com +5 and 4 points of virtues. This all assumes no bolts from the blue to punish such a player. Here's what you're looking for (in order of the recipe's cheesiness):
The Covenants errata (3rd item in the errata) has that +3 for all tractatus qualities. So +3 +1 scribe +1 binding +1 illuminator +3 resonances.
Essential Virtue (major) applied to Communication with a narrow enough field that covers writing tractatus. Technically, "educational writing" is probably suitably narrow since "good aim" is suitably narrow. There's another +6.
Seasons are explicitly fluid with the exception of laboratory work, in which case they are explicitly not. So, for each of three seasons in a year we could spend a month writing a tractatus, a month doing a second thing, and a month doing a third thing. You make sure you do your writing during the signs Sagittarius, Pisces, Gemini, and Virgo. Make your virtues Mutable Good Teacher, and for a super extra cheese recipe Mutable Essential Virtue (major or minor doesn't matter at that point).
So that's 3 +1 (scribe) +1 (binding) +1 (illumination) +3 (resonances) +5 (Com) +6 (Mutable Good Teacher) + 6 (Essential Virtue) = 26. If we drop the cheesiest (Mutable), then we still have 23 but need 4 points of virtues.
So the maxima are:
ArM5 only: 14
ArM5+Covenants: 17
ArM5+Covenants+RoP:M: 23
ArM5+Covenants+TMRE: 20
ArM5+Covenants+RoP:M+TMRE: 26
Thus 26 is possible by the rules... And then we all laugh as the magus finishes writing his first tractatus, walks outside to announce he is an even better writer than God, and gets struck down for his blasphemy, the book burning up with him. Fun for all!
Chris
"Explicitly"? (Are you sure you mean this?) If so, where are you drawing this from? (Because I find almost exactly the opposite, a strong implicit statement that they are not fluid, and are just as tied to Seasons as any other experience or task; esp see p 165 col iii, par 4, et al.)
I ask just to make this clear both to myself and any newer players reading this. 8)
Other than that... mmmm... a fine and piquant fromage, most def! Pass the crackers! 
Smurf's Parma...
I think Lab and Magical activities are specifically and explicitly tied to the season. Other "seasonal" activities are not, such as writing or study, and these are indeed fluid. I will check my book later to make sure.
Yes, I do mean explicitly. I'll put the quote up on Friday. I won't have that book back until Thursday night, and I won't have time later that night.
Yup.
Chris
It'll take a few more days. More than half our group were very sick last night. I still don't have my books back.
Chris
No prob, standing by, still curious. 
Meanwhile, I'll lay out what I see, why I'm asking...
The layout of Chap 10 does not appear consistent - the main heading of "Experience and Advancement" has its first two sub-sections titled "Using Experience Points" and then "Advancement", but then a lesser heading appears "Writing Books" (same font size, not bold). (Possibly an editing decision due to spacing? who knows...)
However, under Writing Books it says:"Once the level is determined, writing commences. For every season spent writing, the character accumulates a number of points..." It goes on, mentioning "seasons" several times. Nowhere does it say "time totaling a season" or "a season's-worth of writing" - it speaks of seasons as single (and I assume, indivisible) units.
I do remember somewhere once seeing some suggested rules for breaking all study, labwork and etc down into smaller units of time - but as I remember it that was either was fan-based (i.e. a houserule) or optional. I'll admit that while there can be a rationale for magic/labwork only working "season by season", there is less so for writing and other study - but that's how it's laid out in the Core Book, and this is, after all, a role playing game for telling stories, not a simulation of RL.
IIRC it is in the Triamore Book , so it was official but very optional