So, who's playing the grog, and which grog is he, and does he have any stealth to speak of? 
JL: Sorry, no idea. I don't even remember what grogs are with us 
Not-so Quick search :
Isen: Bernard, Brionne.
Tranquillina: Jehanne, Falko
Fiona: ???
Jacques: Orrand
Orrand isn't very stated, so it must be one of the other 4.
Yes, save that, unless the grog is discovered (in which case we need to use force, there's no need for all the magi to teleport inside the camp. One is enough.
And of course several things will go wrong 
No plan survives the first contact with the ennemy.
I can't find stats for Brionne. Of the others, Falko handily has the best Stealth. He's also got great Quickness which could be useful. Plus he'll be more fun to listen to
Casting time for Tranquillina (we can rest two minutes between each spell).
- Spell to shrink Falko: As Preternatural Growth and Shrinking, but -1 magnitude for Diameter instead of Sun, +2 to affect a Size +5 target, for at least level 20; rolling up to reduce his size as far as possible, but not below 0. Casting Total: Sta -3 + Mu 9 + Co 27 + Talisman attunement (Corpus) 3 + aura 12 + stress die 4 = 52, halved is 26. Level 20 would shrink by -2, so level 25 would shrink by -4? That makes Falko size +1, which is small enough to cast normal Corpus spells on - probably good enough.
- Spell to shrink herself: As above, but an additional -1 magnitude for Personal instead of Touch, for at least level 15; rolling up to reduce her size as far as possible, but not below 0. Casting Total: Sta -3 + Mu 9 + Co 27 + Talisman attunement (transform self) 4 + aura 12 + stress die 6 = 55, halved is 28. Level 15 would shrink by -2, so level 25 should shrink her all the way to Size 0.
- Isen, you do want the illusion on you destroyed, yes? Assuming so, Tranquillina has Unraveling the Form of Imaginem as a formulaic, at level 10: Sta -3 + Pe 14 + Vi 5 + Mastery 1 + aura 12 + stress die 8 = 37. Cancels an Imaginem spell of level 10 + Unraveling 3x(Mastery 1) + 10 + stress die 4 = 27, easily beating the illusion's spell level of 5 (hmm, maybe Isen could have cancelled this himself).
- Tranquillina also has Veil of Invisibility: Sta -3 + Pe 14 + Im 10 + Mastery 3 + Talisman attunement (suppress image) 5 + aura 12 + stress die 3 = 44, good enough.
- And when it comes time, she'll cast The Ear for Distant Voices to eavesdrop on Falko's surroundings: Sta -3 + In 6 + Im 10 + Mastery 1 + aura 12 + stress die 9 = 35, good enough.
(Edited to add: eep, all of those rolls should have included a -1 penalty for her Vis Allergy. Nothing was on the edge though.)
Isen and Tranquillina will both take a hair from Falko (or something else easier to keep track of?), and a stone from the ground at their setup point in the forest near the giants' fort.
I assume Isen will spont the spells that capture Falko's image and voice. Then we should let Falko practice for a few minutes and make sure everybody gets used to what's happening. We should warn Falko in particular that he'll still cast a shadow.
Isen, will you make yourself invisible, or do you want Tranquillina to do that?
Also, since invisible people with shadows will prefer darkness, Tranquillina will cast Eyes of the Cat on herself and Falko. Even without duration reduced to Diameter it's only a level 5 spell, which she can cast with non-fatiguing sponts: Sta -3 + Mu 9 + An requisite 8 + Talisman attunement (eyes) 6 + aura 12 = 32, fifthed is 6.
Alright travel to the [strike]Steading of the Hill Giant Chief[/strike] giant chief's hall is without difficulty. There are a few farmers that they spy, but they keep to themselves, and no apparent patrols on the road.
The charred remains of the palisade is there and no work appears to be going on to repair it.
Falko is invisibled and then...
Fiona's sitting this thread out (well, actually, the player is, but still), except for enjoying her time with the Blacksmith, but her new shield grog Jehanne is with the group.
Brionne's stats are here, but I don't know if he's been advanced since 1220. He's not on the Wiki yet, though.
Yes, he will.
Perdo 6 + Vi 4 + Sta 2 + Aura 12 + Talisman 3 = 27 / 5 = lvl 05 without fatigue.
Using the general guideline to "cancel effects of a speficif type with level less than (level + 4 mag + a stress die) means that, even if going for touch range, he can cancel Imaginem spells of lvl (5 + 3 mag + stress = 20 + stress), which is enough.
Yes, he will.
Isen ReIm is 26 + 2 + Sta 2 + Aura 12 = 42.
Using ReIm base 4 (make an object appear, to one sense, as it it's attached to an object defined at the time of casting), +1 touch, +diam, + 1 to affect a changing image, +1 to have it change along the object, = lvl 20.
He's gonna use the same one with sound, only with duration Concentration, so that he may drop it if needed.
WTF??? Invisible castle is no longer registered domain??? And I haven't found a diceroller that allow me to link results
It should be ok, but there's always a slight botch chance.
He'll hesitate a little. He doesn't like to lower his parma like this, but he sucks so much at PeVi, he's not sure he can do it. He won't say this to tranquillina, of course.
Just do it. I prefer to avoid spontaneous magic, given the chance. Thanks.
((Hey, cool, it's already a Touch range spell!))
"I understand your caution with spontaneous magic; but I know this effect well," Tranquillina reassures Isen, placing her hand upon his shoulder. She then casts Veil of Invisibility upon him, without words or gestures just to show off. 8) ((Sta -3 + Pe 14 + Im 10 + Mastery 3 (no words/gestures penalty) + aura 12 = 36 even without the die, and there shouldn't be a botch chance.))
Of course, he'll say nothing.
But in his foremind? Luckily, he can ascertain at once that he's invisible, and thus that she has cast the right spell, because, otherwise, there would have been no way for him to know what she's done, which would have made him very uncomfortable 
So, I guess we are set, then.
Oh, invisible castle seems to work again 
So, roll for the 2 Rego Imaginem spells:
Gerg, why don't you run Falko...
Everyone else is covered up by other threads, and I don't think it will interfere too much otherwise.
((Roger that.))
Falko is moderately freaked out by the whole image-and-voice theft. "Bless my soul," he says as he stares at himself, hovering above a tree stump, saying his own words back to him while he can hear nothing from himself. Tranquillina leads him back and forth around the nearby trees for a few minutes, until he gets more used to it; she points more than once to his shadow, warning him against being too bold in well-lit empty stretches.
As night falls, Falko starts creeping across the stretch of land between the forest's edge and the charred palisades. He doesn't go that much faster than he would if he had not been magicked up - although his ability to see the terrain in the dusk is far better than he is used to. "I'm alone, but I don't care," he sings without being able to hear himself at all, "I strut right by with my sword in the air...."
Falko makes his way inside the palisade, he waits for a bit, and the door opens and a giant comes out. He is able to dart through the open door just in time. The stairwell is partially blocked by a giant piece of wood, but it has been hacked out well enough with a make shift stairway. Making his way upstairs ther are four rooms with closed doors...
Tranquillina is now eavesdropping on Falko's surroundings. If Isen wants to spont a spell so that there's two-way communication, he may, but let's not make any noise at Falko's location...! Of course they can both see his image and hear him, although much of the latter is bad singing in Flemish. Speaking of which:
"One, two, three, four, who knows what's behind the door...." Falko chants without hearing himself, rubbing his chin in thought. He is truly enjoying not having to censor his musical impulses behind enemy lines.
How is this hallway lit? The poorer, the better.... Falko takes note of a spot on this near end of the hallway where his shadow is least noticeable. Then, on the theory that the valuable stuff is behind the most defenses, he goes to the fourth door, swallows hard, then knocks firmly upon it. Immediately he tiptoes back to the shadowy spot, from which he can see and hear the door he knocked on; in particular he tries to listen to whether any locks were engaged. ((Awareness roll for the latter: ... you know what, never mind, he's Per -3 and Poor Hearing 
He'll stick to seeing whether anyone opens the door.))
Well...no one's opening any doors...
It's either pick a door or wait...
If Falko picks a door, pick 1-4, or option number 5, for waiting...
No problem, that's good information. Falko remembers he's supposed to be communicating with the magi, and starts describing where he's come. "Nobody came when I knocked on the door; hopefully that means nobody will get upset when I open it. Just in case, though, I'll have a diversion ready." He takes a silver penny from a pocket and holds it in his throwing hand. (I guess his sword's sheathed right now.)
Falko picks door number 4; he turns the knob (or whatever) and pushes it open wide enough to go through. Unless he sees someone staring right at him, he'll quickly step through, but hold the door open with one hand as he looks around the new room with his back against the wall.
(If that door is locked, he'll try number 3, then 2, then 1 until the first one that opens.)
Door number four appears to be a sitting room. There are many stuffed animals of gargantuan size on display in the room... Nothing looks like what's been described. There is also a human sized writing desk in the room, which goes without notice for a while. On the fourth time he passes it he notices that the desk doesn't fit with the scale of other furniture in the room.
((When you say "nothing looks like what's been described", what do you mean? Did Falko get a description of something?))
Falko closes the door behind him. "The last door leads to ... a child's play room? A giant child, that is," Falko reports, poking a couple of the stuffed animals to see if there's anything strange about them. After a few minutes of searching, he notices the writing desk. "There is one odd thing - the desk, here, it's not the right size for a giant."
Falko goes through the desk drawers, the human-sized chair, and so on, seeing if there's anything interesting to be found.
If he runs out of things to do in the room, he'll go back into the hall and see what's behind the third door.
Sorry, I figured he was instructed to look for the long silver chain....
There's a supply of parchment, ink and quills, a couple of pieces of leather and some tools to make a rudimentary binding, although Falko might not recognize it, he can describe it well enough to Isen and Tranquillina that they know what he's seeing. The desk is not sized for a giant child, it is sized for an adult human. There's nothing else in this room of note.
((Oh I get it now ... I thought you were saying that the whole setting wasn't as described ... but it's just that there's no chain around yet.))
As he finishes his fruitless search, Falko sings a little Flemish quatrain about strange markings on paper that magi seem to get so excited about. He sits in the chair for a moment, resting his invisible arms on the desk, noting that the size is perfect for him. Then he returns things to their original places and leaves the room - adopting a general strategy of pulling/pushing doors open to get a glimpse of what's beyond, then moving quickly through the doorway and keeping his back to the near wall while he takes in the surroundings. "Here I go, opening the second-to-last door in the hallway," he says in Latin, doing so.
And behind door number three...
This room is rather large and appears to rap around the other room on its side, going behind it. There is a bed, and in the bed are two sleeping giants, or a giant and a giantess. Well they were sleeping, the process of opening the door wasn't as quiet as Falko would have liked, and it creaked loudly. The giant is looking about, while the giantess has just rolled over and gone back to sleep. After a few moments of being frozen the giant goes back to sleep.
Additional activity in this room will require stealth rolls, because while Falko's voice doesn't make noise here, his footfalls and other noises do.