Lots of various glyphs and inscriptions, some you recognize and others obscure. What stands out prominantly is the inscription "VALDARIUS MCXI" (Valdarious, 1111).
Vulcanus read of this. This is the Vault of Valdarius. The true vault. You had a hunch about this (as we discussed), and you were right.
Hélène is stumped. The mythical vault of valdarius! From what she gathered through her discussions with Antonio and Dimir Taar, this should be an incredible treasure trove of mystical items.
And it is undefended.
Vulcanus. I am sure you realize more that I what this means. But before we go and reclaim your heritage, we must hide it. Whatever attacked andorra before may do so again. And it sure seemed like it was searching for the vault, or something within it. I already instructed the redcap to keep this silent. We should, too. I shall hide this entrance with an illusion, that's already something. Secrecy is our better weapon, anyway.
She'll use a low-level Rego spell to inscribe a circle in the stone floor, like an artisan would do*. Then, while standing in the circle, she'll cast a simple illusion, like if the wall wasn't breached, to hide the entrance to the Vault**. Then, while still concentrating on her illusion***, she'll cast her Circle of Spell Sustaining, to keep the illusion going.
- I figure ReTe base 1, +1 stone, +0 Mom, +1 Part = 3
ReTe = 21 + 07 + Sta 01 + Aura 05 = 35. She can do it even with Base 2 and an additionnal magnitude.
Finesse roll: int 2 + Finesse 6 + 1d10=2 = 10
** CrIm base 2 (affect sight and touch), +1 Touch, +1 Conc = 4
CrIm = 9 + 5 + Sta 01 + Aura 05 = 20/5 = 04. Barely.
Finesse roll: int 2 + Finesse 6 +1d10=3 = 11
*** Pray I don't miss, Concentration 3 + 1 (specialty in spell concentration) + Sta 01 + 1d10=7 = 12
"Wait!" Vulcanus shouts, as soon as he realizes Arachne is using magic. He will certainly try to interrupt her spellcasting before she can finish. (I'm assuming that with Vulc's +3 Strength and Arachne's -2 Strength, that grabbing her arm will suitably interrupt her inscription of the circle. 6 is his quickness/initiative check, if it matters.)
"This is Valdarian," he explains in a voice which makes it clear that the craftsman is unaccustomed to describing what is obvious to him, "Crafted by the greatest enchanters in Hermetic history. Do you really think it is not protected against foreign enchantments? Target that vault door with any magic, and you may find yourself in Twilight, or worse."
He calls for a servant and instructs him where to find his Very Special Book, which he flips through to refresh his memory on the Vault of Valdarius. (Valdarius Cult Lore check 12 to figure out what he knows about the Vault's protections, plus any bonus you might want to award for referencing the book. He will expend a point of Confidence if necessary; this is, after all, the heritage of the most important Hermetic lineage of all time.)
To set the scene...
This door is actually well protected. It is inside the Mercere vault behind a secret wall. B ut this is confusing. Which came first? This vault or the Mercere vault? Why one inside the other? And what of the other "vault of Valldarius" under Dimir Taar's former armory?
The VSB that Vulcanus has can answer a few of these questions, but some mysteries remain.
The Mercere vault does not actually belong to the Mercere. They rent the space. The VSB mentions that the vault is hidden inside another. You may have thought of looking for a secret door in the ruins of the armory, but it turns out that it is here.
What is the Mercere Vault then? It must have been the original covenant vault, with the secret vault hidden within. The arnory must have housed a newer vault, clearing out space to rent to the Mercere.
What could be in here? Obviously stuff that does not get used very often. Frequently used items were kept in the armory, such as the Rod of Transportation and the Ever Lovin' Flying Carpet and the Phoenix Sword. Those are all gone now.
So whatever is in here is ancient, unused, and/or mysterious.
And according to the VSB, it requires two magi to open it; both must be full members of the covenant, one must be of the lineage of Valdarius and one must hold the rank of Pontifex.
Arachne remembers something from a few years ago, back when she was studying under Dimir Taar. Rodrigo of Mercere, who was a Pontifex alongside Antonio, came to visit Dimir Taar and they had a short private discussion. They had some secret buisness to attend to, and Rodrigo was carrying what appeared to be a bottle made of brass and stopped with lead.
(if you think really hard, there may be an alternative way of getting in or finding out the contents 
)
Actually, there was both a misunderstanding (due to my being unclear, I'll confess) AND bad memory from me.
I thought there was a break in the wall, instead of a false one (this is the bad memory), but I wanted to hide the second entrance, not the vault itself (this is the misunderstanding)!
So if both the false walls are still functionnal, the Spider will do nothing. If the second can be detected, she'll cast her spell on it, as above.
That... rings a bell (to me, actually 
So probably to her, too)
Int 02 + Andorra Covenant Lore 1 + 1d10=6 = 9.
Well, she thought about piercing the walls, but this may not be the best course of action (she never did something like this, since it would have taken too much time, yet countermesures are doable). Still, she might nonetheless manage to escape retribution, but she wants this to remain secret, which limits her options.
To Vulcanus
Sodales... I might be able to shrink one of my spiders, send it into the vault. You're the expert here. What do you think of it?
If he agrees, this is probably* MuHe base [strike]3[/strike], +1 touch, +1 diam = lvl [strike]05[/strike].
Her MuHe is 05 + 06 + Sta 01 + Talisman 05 + Aura 05 = 22 / 5 = 4. Hum... Hey! She has a spell focus, with the Mercury from her talisman! First time I'm using this, woot! This adds +5, to lvl 09.
Arachné lifts her ring before her eyes and concentrates, while the mercury within it shines, as she then weaves red spectral webs over the little wooden spider, that becomes even smaller as before. Will this be tiny enough?
- I have the guidelines, but no spell exemple, so may be wrong. Or, more probably, this might not be enough. I want an herbam-based, reverse "Object of Enlarged Size". Ok, based on MOH, this is base 4, so no, not like this.
Oh my. It never occurred to me that the talisman attunements give their bonuses to the magus. I always just assumed they went only towards effects invested in the talisman only. headdesk
(( Don't feel bad, I only figured out how helpful that could be literally days ago as well, and I've been playing Ars forever. ))
Btw, I stumbled upon a variation on the spell I wanted to cast in MoH (excellent book for inspiration), and it is base 4 
So she can't cast it... Unless she takes the time to do it ceremoniously...
To vulcanus: Tell me, how is your Muto Herbam? Do you think you could spont a 2nd magnitude spell?
Intriguing 
Let's see what happens 
Vulcanus glances at the Spider archly. "Do you always flirt so awkwardly? I'll just assume you're out of practice," he replies, without answering her question at all
(OOC - Ryu, while you might not know it your magus would. If this ends up breaking the circle as it's being drawn, it's an automatic botch on the spell. But she could just stop concentrating and let the spell fail. So physically grabbing a maga's arm while she is inscribing a circle could well be taken as an assault since there is a decent chance of sending the magi into Twilight. I figured we were just going with the stopping concentration idea, but I also thought I should point this out.)
bwahahahahahahahgahahaha!
That is something an old fashioned "Killer DM" would latch on to. I am not so concerned about it as long as both players are copasetic.
But yes, thank you for ointing that out. Always feel free to point out little nuances like that.
Hélène is a little surprised by that reply. Maybe it's having had to fend of antonio in the past, but her reply is a little harsher than what she'd have liked
I'll assume you're as uninterested in Muto Herbam as me in you, then
And she regrets it instantly.
As a mate, I mean, not as a sodales, does she say to soften the blow
Yes, although that'd have been fair, too, with a warning (since the character is supposed to know that perfectly). Luckily, since the circle spell was her last spell, we can reasonnably assume he did it on one of the 2 previous ones.
Vulcanus tosses back his head and laughs deeply, in a way that makes it crystal clear he is totally unattracted to the gracelessly aging maga, but his smile is just as charming regardless. "Ah, Miss Arachne, you asked a Hermetic descendant of Verditius about his spontaneity. Of course I gave you the benefit of the doubt in assuming you were not daft." He reaches out and ruffles her hair. "In any case, the vault is not going anywhere; I will spend more time researching it. In the meantime, I'm afraid I have to ask you to leave it alone-- this is one of the great legacies of the Knights of Seneca and the lineage of Valdarius, which you are neither. Can I trust you to respect our privacy?"
(I don't mean to try and quash the adventure, but if the book says it takes a Valdarian and a Pontifex to open, he's going to wait for Carmen's return. And he certainly does not want house secrets to be shared with outsiders.)
I am surprised. Never Dimir Taar, which hails from the same lineage as you do, never showed any problem with spontaneity. My mistake, then.
So, I guess he's just bad with Muto Herbam, thinks Arachné.
She pauses a little
As per your wish... She laughs softly You are close-minded in that, I can tell you, so I am not surprised at all by it. I will, of course, respect your desire, as I am sure Antonio and Dimir would ask me. But don't take too long to investigate it either. Whatever is in there, it may be what the assaillants searched for, so we may all be concerned.
She'll ask him if she can hide the entrance, for she, too, wishes it to remain cloaked to prying eyes. If he agrees, she'll cast the above spells on the second false room if it appears it is no longer efficient at hiding the passage.
Somewhere in the darkness of a cave deep in the swamplands of (???)...
Master, word has come from our agent that the magi of Andorra have discovered a second vault door.
What an idiot I am! I did not search well enough it seems. No matter. I am sure it is in there thyat I shall find what I am looking for. The Brass Bottle that commands one of the most powerful genies known to Hermetic Lore!
Thank you, loyal servant. However, in my self anger I admited my failure and weakness in front of you. Cannot have you repeating it. I must erase your memory now and send you back...
"My lady, should you wish to swear your allegiance to House Flambeau, we would be most happy to have you." Vulcanus smiles, green eyes sparkling handsomely.
Hélène smiles
Why, thank you, sodales. This would be an honor, but, sadly, I am too set in my ways to learn new tricks. And I wouldn't wnat to taint your house's honor and shining light with my dirty little tricks. Nonetheless, I appreciate the intent
Good, I had taken the clue 
Now, how did he know it? The redcap talked? The redcap is the spy? Suspense! 