Is Xenophon someone in the books, or entirely your creation? I don't recall anything about these Duresca Scrolls.
Xenophon/Apollodorus is my creation.
The Duresca scrolls were a collection of documents that were letters between Guernicus and his filii describing a secret agenda of the House to take over the Order, and then eventually the world. They were discovered at thecovenant of Duresca in Iberia. They were presented at the very next Tribunal, but declared fraudulent and destroyed. Soon afteward the purging of House Tytalus became necessary, and distracted from the controversy. And then there was the Schism war that happened, soon after that.
I decided to blow the lid off this a bit sooner than I had initially planned. It also works well that Apollodorus' plans fall entirely apart because of an inadvertant comment from a lowly Tremere soldier who's just read a bit too much for his own good.
I want to make sure you know that I am more than willing to revisit this. If the Mercurian is too difficult to play we can come up with something else. AFAIK, the only places this played out was 1) The Dimicatio 2) the spell to move Mufarjj and 2) The spell to heal Mufarjj. So the impact of a change, IMO is relatively minor, we can account for the vis, and the other two items can be handwaved away...
That is mostly because I have tried to avoid times when I have to spont cast a spell. I was waiting for another mage to show up during the 45 minutes it took me to cast the spell to move Mufarjj to just cast dangling puppet and move him rather than wait. It will be useful when he has to cast healing rituals but not casting AoH.
It is more of a complaint about it being a major virtue. I took it because it fit the house and story but it is very limited gain for major drawback. ArM system rewards creativity for thinking of spells or how to do things with magic. Most of that tends to be the spontaneous magic system. While Korvin can do spontaneous magic it takes so long that in a situation where I do not have 15 minutes to an hour to cast a spell it really sucks.
Now if we were a vis poor campaign it might be different but using 1/2 vis on rituals and a spell that only works if others take it for hurting spont spells is just not worth the 3 points. Comparing it to any other Major Hermatic Virtue leaves it wanting in a big way.
I'm done ranting
I will say, again, it could be changed. Mercurial works, but I think Mercurians need to have a vast repitoire of spells. You could rework your grimoire to some extent.
Oh and this story is mainly about the aftermath, so your Arts will come into play.
Not that it makes a particular difference in the battle, but I cannot believe that I totally forgot that Fiona had some armour commissioned over a year ago. I'll just assume that, since she's not used to wearing armour, that she forgot to go put it on when the alarm sounded. And I'll need to write it up. Ideally, since the covenant is Wealthy, we can afford to make her oversized Chain Mail (presumably using the normal Protection and Load values). If not, then Metal or Leather Scale (preferably the former, since it has more protection).
And in a related vein, I also realized that I never bothered to actually write up the armour part of The Armour That Fits that Fiona brought with her. It's MuAn(Te), with the requisite for the iron fittings on the armour. Unfortunately, Leather Armour sucks. Would it be feasible for it to be Leather Scale or Metal Reinforced Leather with that item description, or is Ivor just going to have to suck it up? (I glanced at the MuTe guidelines, and reversing the Animal and Terram is going to mess up the calculations).
I was just mad because I was thinking of ways of putting out the fires which would be interesting since Korvin can't do Perdo well at all. I had some good ideas then realized I could do none of it. Just pisses me off that Mercurian is so poor of a major virtue.
Once again, I heartily offer Theraphosa's skills in OoHLore5, and other such mundane knowledges.
Hmmm...does learning from a familiar count as the "one season a year"? That would be an interesting precedent...I think in most cases, you are legally your as far as responsibility and tort goes. If your familiar steals a shiny pawn of Vis, it's just like you did yourself. But there's still room for doubt.
I wonder if Apprentices will address this when it comes out?
Although, whether he winds up Triamoran Bonisagus or Guernicus, he's going to need OoH lore, I think. So let's pencil him in for whenever Theraphosa wants, pending legal counsel against it.
Would have to be Winter. Possibly, she can ask about the legality of it in her Correspondences on CoH ~snicker~
Hrm. I see that according to the rules, Thera can teach 1 student, even with Teach 0, but only gains Exposure XP in Teaching. I'd like to argue that it would count as Practice XP (5), since she'd be "forced to practice [it] in an environment with immediate feedback as to how well you are doing."
Let's see, Com 3 + Teach 0 + 3 + Single Student 6 = 12.
If we can get her up to Teach 1, then she could take on Abagael filia Korvin as well. ~cackles at the visual~
Shall I adjust my Seasonal Activities?
Or we could ask our local Guernicus maga, if she's still around.
Sure. That's when I had Ulrich penciled in for being taught anyway, so it works for him.
Again: Light is NOT species.
The fact that this spell requires an ignem requisite to create light at all clearly show that:
Imaginem = species and not light
Ignem = light and not species
There's not a talk of affecting lungs.
If you go saying that Im can create light, and light bright enough to hurt, why not say that imaginem can create foul smells like wreath of foul smoke?
Note that I can take your argument in reverse, in that, even if accepting the notion that Imaginem can create light (which, by the raw, it can't), "your senses might tell you it is blinding but it does not blind".
Well, thanks. I'm relieved. It was a concern to me, and I was bothered by this.
This is interesting. You might want to ask this to... Timothy Ferguson, I believe? Or at least someone more versed in this by me.
I fear this may be something akin to Pink Dot, a discrepancy in the rules.
Yes, this is how I understand it:
If creating an illusion that also emit light, you must use Imaginem (for the illusion) and Ignem (for the light).
Whether it's CrIm(Ig) or CrIg(Im) depends on the highest base.
Oh. I just realise I missed a lot of discussion here, as I'm 2 pages late 
Serf's parma, this would work.
See miniatures, in the Jerbiton section of HoH: S, this (IIRC) covers exactly this kind of thing (aiming an illusion at someone's face). Johnatan has quite a good point about magnitudes, though, and I don't know if this adresses it.
Yup.
For rituals, you need to think BIG.
It also helps if the GM ensures that some spells are rituals due to their potency, meaning they become your specialty.
One (IMO) excellent HR that I found in the army killer spells was that any spell with something like Group + 3 magnitudes for size (I believe it was 3, but am unsure) was a ritual. This insured that almost all the spells of mass destruction/manipulation/whatever were rituals, and thus the domain of excellence of mercurians.
Let the smaller magics to other magi! And boost these Artes Liberales and Philosophiae! A non-negligible part of sponts in done ceremoniously, anyway.
So have Isen, fiona, alexei and the rest clean up the carpet... Add a magnitude, and clean the carpets!
So try to learn or develop useful rituals. These may be because of level, size, duration, or just raw power. Boost AL and philosophiae. You could be our magical artillery/mass builder/whatever! Send letters to other mercurians, asking for rituals they may send you... Even if it takes 2 years to get them, once you have enough, you can learn them.
hope this helps at least a little
Exposure, not practice. Practice involves deliberately trying to find out more about a subject, in this case, Theraposa would be trying to figure out more about teaching. However, since her primary activity is imparting her knowledge to another, she can't practice teaching to the exclusion of everything else, and it must therefore be exposure. She picks up some useful tips as she gets feedback about how Ulrich is absorbing material.
My interpretation of the PC, as it relates to apprentices is that the season of teaching must be from a magus. It can be any magus, which opens up fostering possibilities. A familiar is not a magus.
Also, going to the letter Fiona wrote, Duncan was never part of the Order, as apprentices don't take an Oath, or at least don't take an Oath as a magus, so he has no rights within the Order. He may be hunted, but House Guernicus has other matters currently occupying the bulk of their attention, or at least will shortly...
So Ulrich can be taught by Theraphosa in Winter, but he'll still need to be taught by an ordained Magus/Maga sometime during the year, then? Any volunteers? 
I can tell you who it won't be... 
Except (and correct me if I'm wrong) my understanding, based on the Magic Resistance examples on pp. 85-86, whether Ulrich uses Rego to pick up a chunk of wood, move it over to the magus, and go bambino upside his head or whether he picks it up and hurls it at him, either way it has to penetrate. The example bridging pages 85 and 86, about a "normal rock thrown by magic stops at her skin or clothes" seems to indicate that either way, he has to get a pretty hefty Penetration.
Now, if he were to move a block of wood over the magus's head and let go, then Magic Resistance is irrelevant (Aiming, p. 86), but he would have to make an aiming roll for that, too.
HOh:Societas introduced spells that are Rego based and don't require penetration. Invisible Sling of Vilano is one such spell. Not having finesse makes it risky. Of course he knows enough that he won't easily penetrate.
This did not occur to me as I was thinking of the Harco Map in the Rome Tribunal which had all of the Mercere Portals in the basement of Harco. Not in the village with the warehouses. Just different visions of what the Covenant looks like.
That was from 3rd edition where everything was Hermes Portals. Mercere Portals have a bit more permanence about them and are a bit large, in my mind. I'd say small carts could go through them easily.