How would you do this? Calebais suggests it can happen, but what do you do to a wall to allow you to pass through it? (Presuming you donâ€™t want to simply destroy the wall.)
A) Muto Terram Base 4 (change dirt so it is highly unnatural). Presumably stone that one can walk to would be highly unnatural. Or perhaps it is a mixture of liquids, solids and gasses.
B) Rego Terram Base 3 (control or move dirt in a very unnatural fashion). This could make a section of wall just move freely like a door.
Or what about this? (Iâ€™m pretty sure this isnâ€™t legal.)
C) Rego Terram Base 2 (Shape and form dirt, as if a craftsman had worked on it) with a duration to temporarily rework the stone wall into an arch. Again, I donâ€™t think thatâ€™s legit, but I love the image of it.
"Perdo magic can...destroy aspects of a thing" - Ars Magica 5th pg.78
I would suggest looking at destroying the wall's property of solidity. I would base the base level off of Perdo Ignem guidelines: PeIg 10 - destroy one aspect of a fire.
So change this to destroy one aspect of dirt, at the same level, 10.
PeTe 30 Passing the Stuborn Stone R: Touch, D: Conc, T: Part
Turns part of a stone wall, as large as a door, insubstantial as long as the caster maintains concentration. As the spell ends, the wall regains it's solidity within moments. Those who are still in the wall are pushed out of the wall as it returns to its natural state.
(Base 10, +1 Touch, +1 Concentration, +1 Part, +1 affect stone)
Note with this, the object is still there, in this case the wall. And the wall still blocks vision, so you may be leaping from the frypan into the fire. Also the spell's limit on size affected with stone is one cubic pace, so that limits the thickness of the wall.
Well my attempt at spell design,
To actually, literally walk through the wall would require something along the lines of the above mentioned MuCo(Au) 30 baseline, "Turn a human into an insubstantial object". Since you'd need a Duration more than "momentary", a bit more.
However, it's not clear if that "insubstantial" is the same as "non-corporeal"- stone walls can easily block all Aurum effects trying to pass thru them.
Either way, you'd also need a way to actually do the moving, so that would add a Rego element - once you're insubstantial, your feet ain't gonna get much traction to get you where you're going.
(Also there's the question of clothing & equipment, but that's been discussed elsewhere.)
Alternately, Rego Corpus Guidelines for Lvl 10 - "Transport the target instantly up to 10 paces" - that should serve to get through a wall - not "walk" thru, per se, but it'll do the job.
However, I, for one, would be loathe to teleport blindly past a stone face- no telling what you're getting into. So another spell would be wise...
Intellego Imagonem Lvl 1 - "Use one sense at a distance" (Note that if there is no light, you still can't see, and CrIg would be problematic in that you can't cast a spell where you can't sense. So, another spell to get some other sense at a distance, perhaps touch, where you can then cast a light, to see where you're teleporting.
Muto effects should work as well: you turn parts of the wall ibnto a gelatine-like state, that you can cross walking slowly. IIRC there is a spell that does basically the same with Sun duration, where you enter the earth.
Ah... see, I was looking for this for option C. Actually, it was my original option A. I knew that there were some guidelines with "destroy aspect" but didn't look up the Perdo description. Now, will the destroyed aspect return at the end of the duration, though. (Since most Perdo spells have momentary durations, I'm always a little unsure about this.)
Sadly, Corpus isn't a solution for the practical problem at hand. And I wasn't worried about diameter/concentration because this is going into an enchanted device. Perhaps like this:
The Wizard's Door
When activated by performing the proper ritual, this stone (set into a floor touching the wall) turns part of a stone wall, as large as a door, insubstantial as long as the user maintains concentration. As the spell ends, the wall regains it's solidity within moments. Those who are still in the wall are pushed out of the wall as it returns to its natural state*.
(PeTe 40, Base 10, +1 Touch, +1 Concentration, +1 Part, +1 Stone, +10 levels unlimited uses)
*Which apparently is something Calebais did not think of.
Although if PeTe 10 is the right baseline, Muto or Rego would be far easier.
Well depending upon what you really want out of "walking through walls" I might suggest the spell below fron the level 10 -15 spells list.
Wall of Accomodation
Muto Terram 15
Range touch Duration concentration Target part
A section of a stone wall is changed into an open archway just large enough for a size 0 human to pass through comfortably. ( There is a common level 20 variant of this spell that has an herbam requisite and not only works on wooden as well as stone walls but also places a simple door in the archway.) (Base 3, +1 magnitude stone, +1 magnitude range touch, + 1 magnitude duration concentration, + 1 magntude target part)
The guidelines suggest that it is easier to kill living things with Perdo , than to remove properties.
The Ignem guideline is 10 , but 15 for Aquam.
My reasoning would be that Terram is higher by at least one magnitude again ,
and one higher for affecting stone.
So Base 25 to remove the solidity of a stone wall for the duration of the spell.
â€œFire or air are more supple, and so easier to manipulate (or perdo) than more "solid" elements.â€ - Xavi
I would then suggest the difficulties be:
PeAu 10 - destroy one aspect of air
PeAq 15 - destoy one aspect of water
PeIg 10 - destroy one aspect of a fire.
PeTe 15 - destroy one aspect of dirt
I agree with Ravenscroft about increasing the difficult of destroying the properties on Terram. I would put it on par with Aquam thou. I agree with Xavi on the idea that fire and air are more supple and at any given moment changing. I also view the arts of Terram and Aquam dealing with matter of the art, while Auram and Ignem focus also on the forces that affect the art, (To steal a bit from Mage).
So without further ado, I kindly submit a reworking of my original idea, Passing the Stubborn Stone (in the format of the Wizardâ€™s Grimoire):
PeTe 35 Passing the Stubborn Stone
R: Touch, D: Mom, T: Part
Turns part of a stone wall, as large of an area as a door, insubstantial for a moment. The moment is long enough for the magi to step through the wall (one pace). If for some reason the caster is unable to finish journeying thru the wall, the magi is pushed back the way they came, as the wall returns to its natural state. Note with this, the wall is still there and it still blocks vision, so you may be leaping from the frying pan into the fire.
The magi Ragi the Stout, an Verditius, reworked his spell to include a failsafe after spending a season as one with the stone. Ragi increased his understanding of the art of Terram along with knowledge of the structure he now was a part of, but has no wish to recreate the experience.
(Base 15, +1 Touch, +1 Part, +1 affect stone, +1 special affect)