It does. I'm not sure if it affects parts of stuff though. If you stick your arm into a circle, can that be turned into a rock? When extended into three dimensions I would rule that it isn't an infinite cylinder. Either a sphere or a ellipsoid or cylinder of reasonable height.
By RAW, yes.
One of the things that needs to be considered is what constitutes breaking the circle. Something physically crossing it, though the underlying ring stays intact, is the circle then broken? Or does the circle require some physical disruption? Neither of these approaches are wrong, it's just something that needs to be discussed with the troupe, or decided by you, as the SG (I remembered you're the SG).
Of course, there could be a soft rule, of just asking the players not to do this, not forcing you, as the SG to make a ruling interpretation about circles, so long as they don't make them ridiculously large.
Yeah, we've had discussions of this one, regarding just how large a circle you can actually get under the RAW. (Answer: it has to do with the 1-in-100 chance of botching a Concentration check each round of drawing a circle, and what the consequences of doing so is.)
Note that there ARE virtues that allow you to draw arbitrarily large circles: Cautious (Concentration) can keep you from botching a Concentration roll, and the Warding virtue from HoH:S (in the Ex Misc section) lets you ignore the roll altogether.
If one of your players WANTS to be a warding specialist, you may consider just having them take one of these virtues in order to make a rules hole into a rule point.
The problem is not (just) extremely large circles, but rather what the removal of need for Size magnitudes means practically. This goes mostly for Momentary duration Ritual spells such as Gift of Reason (increase multiple people's characteristics) or Touch of Midas (create as much gold as can fit into the circle?) - all at a spell level equivalent to Target: Individual.
My houserule already covers these problems, I'm just interested how far this can theoretically go by RAW.
A SG can resolve this in many ways - also by house rules.
If the guards on gates and towers do not notice somebody slowly drawing a ring around their town, or do not react to it, they are most unlikely medieval people.
If a lone house is not guarded by at least a few watchdogs, there are many ways for mean spirited people to kill all its inhabitants without magic.
If magi find ways by Virtues, Abilities and further magic to first draw their circles surreptitiously and after the misdeed also remove their traces, they have invested a lot more than inventing a T:Circle PeCo spell.
If the spell is cast often enough, in a certain area, I might even go as far as the warping to give the inanimate objects some warping and perhaps flaws consistent with that source, developing some crude intelligence, even. An unintended side effect of the spell...
You want to kill everyone in a town? I recommend: PILE OF CLAY!
PILE OF CLAY - CrTe - Gen
R: Touch D: Diam T: Ind
Creates a square sheet of clay 10 paces thick. At level 3 this is one pace, by one pace, and it increases with increasing level. This can be extremely lethal if dropped from a high height.
Base 1 +1 touch +1 diam +x size
At level 5 its ten by ten. At 15 its 100 by 100. At level 25 its 1000 by 1000. At level 35 its 10,000. At 45 its 100,000. At 50 its Something like 300,000 by 300,000.
The city killing perdo corpus spell would be level 25ish. Plus it would require random virtues and tricks to not have the circle broken. This is a vastly more effective way of murdering a city full of people. (You technically need to fly, but still.) Magi are good at killing mundanes. Even other magi there are better ways to target someone inside a building.
The other thing about ridiculously large circle spells: if they are deemed too powerful, they might just be made a ritual by SG fiat.
Under the guidelines there are multiple ways to easily create army/city killers as Lamech just demonstrated. Should they really be possible without being rituals. That's really a question for the troupe. I can't tell you to do it that way for your game, I just know that the RAW exists to allow any number of things, but don't forget about the escape clause (sufficiently powerful spells can be deemed to be a ritual).
I'm quoting myself, because that's the takeaway, IMO. How do you want circles to be in your saga will make a huge difference in the kind of saga you have. No one can answer that question for you and your troupe, all we can do is arm you with the information.
It was an example of a circle target not being worthwhile. In fact it was an example of a circle target NOT negating the need for size. What they amount to being is not large, but multi-target. You can get a group of people without additional magnitudes. Mass healing or whatever. The prices is its basically worthless in battle. The main result is that healing or boosting spells can be done on large numbers of people and vis costs saved.
Making a spell a ritual adds it's own problems. Since you don't have to roll to extend the casting time the question isn't "How far am I willing to push my concentration rolls?", it's "How big a circle can a draw during the hour plus I now have to cast this spell. The practical size of ritual circles is huge, a mile diameter is pretty doable.
A ritual, though, and this is my own opinion since RAW is inconclusive, is always at risk of botching. Botch dice is at least 1 + the # of pawns of vis used, less subtractions from Golden Cord, virtues and spell mastery.
You're also leaving out what constitutes breaking the circle. If crossing the circle breaks it (especially as it is being scribed) then it is automatically a botch. Circles are problematic, period, and the troupe still needs to decide what they want from them.
I allow large circles with no size bump extra magnitudes.
However, I'm also a bit of a fiend for enforcing reality when trying to draw large circles.
Drawing a large circle on empty flat ground, such as a parade ground using post and string is no problem. If you want to draw a circle around a town, your magus is going to have to
a) account for landscape, inconvenient boulders, gullys, trees, randomly inconvenient houses, etc
b) account for annoying peasants, livestock, weather messing up his huge circle.
c) not fluff his concentration roll while walking the perimeter
d) not draw the attention of spear wielding locals who take exception to a wizard drawing circles around their town
I'll quite happily allow large circles if my players are sensible about it. One of my players aims to use creo corpus to boost the stamina of the entire town he lives in (custom setting, no peasanty problems here) and is planning on using the towns large central piazza to carefully mark a circle out, then invite all the townsfolk into the circle. He'll use guards, assistants and post/string to measure the circle out and keep everyone from trampling it.