Let's say we have a spell, tear down the wall (Re/Te base 3 unnatural movement, +2 voice, +1 stone, +1 part, +1 size) It allows you to tear down a part of a stone wall, a rather large part, up to 10 cubic paces (weighing in at around 20 tons). Probably enough to tear a small stone house from it's foundations and toss it into the barn.
Could the same spell be used to tear up a part of a paved road?
The effect is pretty much the same even if the individual stones are not held together by mortar and are on the ground instead of stacked upon each other.
Or a stone quay, or a bridge for that matter.
I suppose it would not work very well against a large pile of rocks since it's not target group, but how about tearing parts off a cliff face?
I guess you catch my drift.
The Rego [insert form/element] spells that allows you to manipulate a given amount of matter can be used in a wide variety of ways that might not be in line with the intention of the original spell design.
How much does the intent of the spell as designed limit the use of it?
I think it may depend on the saga and the storyguide as to whether or not it would be allowed.
For that particular spell, as long as it included a Finesse roll against, oh, I don't know, 6+ (or maybe 9+), I think I would allow it on the spur of the moment with a warning that I would have to think about whether it would be allowed again later.
My issue is, if you allow this type of changing of the specified target for one spell, you have to allow it for all, and it's very difficult to predict what effect that could have on the overall magic system.
Generally speaking, I'm pretty strict about what spells can and can't do. A spell to turn you into a wolf can't turn you into a goat. A spell to cause fear can't make someone happy. A spell to tear down a wall can't tear up a road. But that's me... your mileage may vary.
My own interpretation is that they are not actually all that flexible. There's a few reasons that support this. First is that there are virtues that give magi greater control and flexibility over their spells, altering a spell then might require a virtue or special design of the spell.
Second, this goes with the overall flavor of magic in Ars, is that words symbols and themes have power when fueled by magic. A spell designed to destroy a wall, logically should be able to destroy a floor or ceiling as well, but the concept of a wall is what's being attacked. It's likely that a magus might have trouble using such a spell. Having said that, it's most likely a novice magus that would design a spell to be so specific. A wizard casting it spontaneously or designing it in the lab with a bit of forethought could likely correct for that without adding additional difficulty.
But bottomline, unless they state in the spell's design that it can destroy things similar to a wall, I'd rule that it wouldn't work properly, magic is an art not a science and it has certain quirks.
I would allow it. But a better idea is probably to reword the spell to something like ~shatter/move apart a bunch of connected stone or similar material...
The spell can do it, it´s just a matter of how the effect is worded. Which is why i consider this a drastically different thing than your other examples, as those are only making use of the same baseline to achieve very different effects, while the "tear down a wall, tear up a road" is using the same baseline to do virtually the same effect.
I agree. I would probably allow a single formulaic spell to do both of these jobs, but only if the description of the effect was worded right. It the effect specifically targets walls, then it can't target roads.
For example, if the magus had a Focus in walls, then he might have invented a version that only targeted walls.
I don't think that you want to be either too rigid or too flexible. This case (target both walls and roads with the same spell) seems OK to me, but it is basically something that your troupe should decide to your own satisfaction.
Generally speaking, when in doubt I say:
base spell: only affects what he was obviously made for; finesse may be used to overcome that if I feel like it's interesting when i'm SG.
if you had any '+ flexibility" magnitude in its design, I'm generally not using finesse : the spell is "intrinsically" flexible and you paid for it when designing it.
I would say, for what it's worth, that the 5th ed rules can be rather confused themselves on matters of specificity. If one has a CrIm or MuIm spell to change how they look, is it only capable of producing a single face, or any number of faces? If I have a spell to lift stone, can it lift any sort of stone, or only one variety of stone? If I have a CrCo spell to heal light wounds, can it heal all light wounds on all people, regardless of type of wound? If I have a spell that conjures up a building, are the shape, size, and type of stone all set, or are any of them flexible?
Edited, because I had somehow gotten crossed between a size +1 and size +3 spell, since size +1 spell won’t do much damage to anything except a small house.
So, let’s go with a size +3. A size +1 tear down the wall won’t do a whole lot to a castle wall.
The guidelines for size +3 allow for removal of one thousand cubic feet (10x10x10). Let's presume that it is designed to remove those exact dimensions. On a wall, that's pretty good since castle walls ranged from 7 to 30 feet for medieval castles. 10 paces will just about clear out any but the thickest wall, and it will likely cause enough structural damage in the process that the wall comes tumbling down, regardless of how thick it is. Or a couple of judicous castings of this spell might be necessary, still makes quick work of a wall.. On a road, removing a 10 x 10 x 10 section is less effective, since you're really only doing serious damage to a 10 x 10 area, the depth of a road is just not that deep.
Now, were I a clever magus and had designed the spell such that I could vary the dimensions of the spell... This is where I'd bring a finesse roll into the picture. If they want to do it without finesse, they get 10 x 10 x 10, or whatever dimensions they designed into the spell (20 x 10 x 5, 2 x 10 x 50, whatever). If they wanted to vary the dimensions at casting up to 1000 cubic paces, then they would need finesse to control the magic and it always requires a finesse roll to get the dimensions they specify at casting, even if going for a 10 x 10 x 10 shape. This spell is now much more useful against roads, since it could effectively destroy a road for up to 200 paces long, 10 paces wide, and half a pace deep (20010.5=1000) It is also a bit more useful in tearing down walls, because they can actually finesse it to breech the full depth of the wall.
For the pile of rocks, I'd see difficulty in using this spell Although removing a critical rock from the pile could also be useful, and I would allow the spell to remove a rock, which might have an effect, but not as useful as the caster might hope. A spell that went after a Group would be more effective in this instance.
For the cliff face, there is a spell that already exists, Cascade of Rocks Level 40. Base 4, +3 Sight, +1 Part +4 size, your +1 size probably wouldn't bring down much of the face, and again, this spell doesn't have finesse, so I'd say it was designed to bring down the appropriate amount of rock along some predefined dimension (probably not roughly equal dimensions of 10,000 paces, but that's up to you as SG, and/or the player when they invent the spell).
A base individual for stone is 1 cubic pace, multiplied by 10 that's 10 cubic paces, not 1000.
To get up to 1000 cubic paces you'd need another 2 magnitudes, and tearing down over 2000 tons of castle wall would certainly be impressive.
That's comparable to a solid piece of rock bigger than a normal house (and yes I know some houses are bigger than others)
Apart from that you do have a good point about finesse.
Yes, you're absolutely correct. I had scaled that spell up, but never mentioned it was a size +3, and I edited my post to reflect that, because as I read your spell it didn't make any sense. A size +1 spell as you'd defined in the OP won't do a lot of damage to a wall, unless it's a standard stone cottage type of house, perhaps a manor house. It certainly wouldn't do any real damage on a castle's wall without repeated casting. Archer's will have picked you off long before that becomes a problem when the best you can do is 1x1x10 sized holes available at size +1, so I increased it to size +3, where you can do some decent damage at 10x10x10.
So, the spell is more difficult that you initially proposed, unless you're just interested in taking down a peasant's house, or maybe a poorly made manor house where coul could do 10x1x1 hole in a manor house just makes it more breezy. And I'd say it has a chance at bringing down a peasant's house. In either event, you probably need a casting or three to make it truly destructive. And against a castle, forget about it.
This is something that simply is not defined btr. And it is problematic, or can be, esp if one looks to the rules for specific guidance (because it's just not there)...
SG's have to take everything into account, and an interpretation of one Guideline may not be parallel to the interpretation of the very next Guideline...
Maybe - and I'm certainly of the same stripe - but not in every case.
Look at the CrMe Guidelines (p 148)...
Level 3: Form words in another's mind Level 4: Put a thought or emotion in another's mind Level 5: Create a memory
Few SG's would require that a Level 3 effect would only put 1 set of pre-determined words into a mind, and the canon Words of Unbroken Silence seems to support that. Sim w/ the Level 4 "Put a thought" - it's a single thought, but variable from casting to casting.
However, that same Base 4 "emotion" works differently - that has to be predetermined according to the canon examples (both Panic of the Trembling Heart and Rising Ire). Yet by the time we get to Level 5, we're back to perfectly variable, ala Memory of the Distant Dream.
Why? No answer can be found in the rules, I guarantee you that much!
A simple CrTe effect creates a boulder - but in what shape? Is it a perfectly spherical boulder, or a square one? Triangular would be handy sometimes, or natural appearing... does a perfectly geometric shape make it easier or harder to create? Does that require "+1 magnitude for complexity"? Maybe... and that's one way to approach the problem, but only one of many.*
(* These are rhetorical questions. Please answer them in for yourselves, thx.)
Creo and Muto Imagonem are no different - how variable can the illusion be/become? Some are very narrowly (excessively?) interpreted in canon, some seem quite flexible. Same is true with many Creo and Muto examples, which either create "some thing(s)" or change something to "some other thing(s)" - some canon examples are extremely narrow, and some are not, but there's no reason to have such restrictions nor to gauge the flexibility, and no explanation how to understand when it's restricted and when not.
Best solution is to figure it out for yourself - use the Central Rule, and judge according to your Troupe.
(The actual explanation is that these are legacy effects - and once upon a time (in earlier editions), it was far more of a SG judgement call and less well defined. Over editions, the spells were kept, but the judgement behind them left undefined and unaddressed.)
Rego is pretty straightforward - It moves "stuff", being defined by the material and the Form*. Same with Perdo - material gets destroyed. (Intellego rarely falls into this particular grey area.)
(* Terram is open to some interpretation as to whether a spell that destroys metal also destroys everything less than metal (stone, glass, dirt, sand, etc etc) or whether it's specific to one or the other unless additional magnitudes are applied. SG needs to make that call too.)
So, you redefine the spell not in terms of "a house" or "a road", but in terms of "the material" that is getting tossed around. It moves "stone" - a house, a road, a wall, a cliff - all fair game, because stone is stone is stone, and a Rego spell just doesn't discriminate (unless you really want it to - and that's pro'ly +1 magnitude for Complexity).
(It would need T:Part or :Group to be practical. Altho' T:Group might toss 1,000 paving stones* around, it could not be used to rip into a solid face or bedrock without +1 magnitude for that "Part" option, and T:Part does not allow multiple individuals as targets, regardless of size - the two never overlap in the base Guidelines.)
(* Assuming a 1 pace boulder = ~2.5 metric tons and a 1 kg (2.2 pd) paving stone)
As a side note, here are some houserule interpretations that I apply when looking at such (loosely supported by various Guidelines)...
Rego: Movement - base = "as fast as smoke rises", +1 mag = "as fast as a man runs", and +2 = "as fast as a horse gallops". (Faster is direct-damage speed, and very hard to control/use for long-distance movement. Exceptions are made with tiny bits of material and direct-damage spells.)
Fine control is very slow, as above (as w/ Unseen Porter etc). Coarse "throwing/repelling/deflecting" gets a +1 magnitude consideration - exchanging control for power/force. So stuff does get "tossed around" if that's the goal (tossed out "as fast as a man runs", = several/few paces away), but to rip up something and place it carefully or toss it a long distance would take more magnitudes.
That's why you have an arrow ward, or are invisible, or shapeshifted as a sparrow, or something. Archers need not be a problem.
Although this is off-topic, I think that if it is in the right place a 10 cubic pace hole may well be a big problem for a castle wall. Down in the foundations, at the right place, you might cause a large section of wall to collapse, or a tower to topple. Of course, the caster would need to be guided by a bit of siege engineering knowledge. But that's not impossible...and a lack of mundane knowledge might be compensated for with Intellego Terram.
I like R: Pers, T: Sight.
Ofcourse, I'd only discover a weakness "visible" from where I'm standing, but that's all I can target anyway, neh?
Makes for InTe 10 (Base 2, +4 Sight) - maybe I'd lke to add a duration so that I can view the castle from different angles?
I threw this out there because Intellego sometimes makes my head hurt, and I was away from my MRB.
Here's what I get Sapper's Delight identifies the weakest part of a wall that you can see. (Base 4, R:Per, D:Mom, T:Sight, +4) Which makes it InTe 20. Base 4 is to determine one mundane property of an object (in this case, it's weakest point). If a weak point were actually visible, a version could be made that is Base 2, which would only be a 10th level spell (this is where a Seige Engineer would be able to do his work). A 10th level spell is with the realm of being spontaneous by a specialist, or someone with a focus in walls.