I agree that it is problematic in a number of areas, I wish there were some impetus to smooth these problems out instead of sweeping them under the rug and engendering hostility whenever someone wants to use city and guild in conjunction with anything else.
Saying I'm never going to agree with you is not hostility. Vigorous debate and strong opinions are not hostility. Invective and questioning the intelligence of the other party is hostility.
I was not referring to you, and hostility can be couched within vigorous debate in a number of ways, primarily when the attitude becomes one of claims of authority or superiority in an attempt to conclude the debate without addressing the other person's perspective. Again, not referring to you.
So just for clarification (and I do agree that the Aegis needs to Penetrate to be effective) then what happens when it fails to Penetrate?
- Creatures with Might can enter
- Spells and effects cast from outside the Aegis still need to Penetrate the Aegis's level to get through
-This is the capper-
- Do creatures with Might and magi/wizards/spellcasters have their powers reduced by half the level of the Aegis if it fails to Penetrate?
If I use CrTe to create a stone tower with duration moon, and it fails to penetrate a magical creature, can they walk through the stone walls? Because that is what this discussion feels like to me...
No, you just can't place it on top of the creature crushing it. Read the section on Magic Resistance, because this is very much similar to a magus walking on a magically created bridge, and it's pretty well explained in the main rule book how Magic Resistance works.
In respect to C&G, my group never tested that, but even we miss things (and believe me, we work hard at trying to throw rocks through every playtest we get)
We think through EVERY rule interaction we can, which is no doubt why many authors get the feedback and scream bloody murder about "How dare they corrupt my perfect artistic vision!". Heck, my purpose in the playtest group is as someone unfamiliar with the magic system (so I intentionally try to keep myself unfamiliar) to ask the obvious questions that people often forget.
As for the list of playtesters, as has been said, email David Chart and ask, but we got involved through an open call for playtesters a few years back.
So if I create a wall of earth, there is no need for penetration to hold someone out, if I create a wall of plants, there is no need for penetration. If I create a wall of ice, again no need, but if I create a wall of power then I have to penetrate? It seems to me that a passive effect, whether a magically created bridge keeping you from falling into a river or a wall keeping you from passing whatever material or effect it is made of should not have to penetrate.
In all of the wall examples, except wall of power, they can be circumvented by climbing it or moving around it. But, yes, they are impeded by the wall, because it has a physical presence. A wall of fire, magically created and sustained, someone with sufficient MR can walk right through it.
As I said, in the Magic Resistance section of the main rule book, a magically created bridge does not have to penetrate. The walls with a physical presence, listed in your example, do not have to penetrate to be effective barriers. A wall of fire or power[1] would have to penetrate to keep someone out simply because it has no physical structure behind it.
[1] Ars Magica doesn't have kinetomancy, per se. Movement of items is controlled by Rego and the appropriate Form, spells to hold people, animals, plants and things stationary are certainly possible, but there isn't one spell that can do it all (except maybe a Terram spell with form requisites when cast) and of course would need to penetrate MR.
Actually anyone can walk through it, the question is whether they take damage. Wards do not do damage, they just keep things out.
True, but that's a quibble. Most people won't willingly walk into a wall of fire, unless they are certain that they can handle it, or there is no other choice/way out.
It is a fundamental difference in how a ward is seen, one where requiring penetration is ridiculous. If I assembled a wall of bricks that was held in place by ReTe magic is would have the same function as one created by creo, though it might be considered stronger as the magic holds the bricks in place instead of just letting them fall away. To me a ward is of similar structure, just not of a material which mundane craftsmen can manipulate.
A wall assembled with Rego probably does not have magic holding the bricks in place, unless another Rego effect was cast on the wall to do so.
But, with regards to wards, you can play wards without requiring penetration, it's certainly a common House Rule, as is an Aegis without penetration. It isn't RAW, though (although some will argue the Aegis needing penetration isn't RAW, either).
Am I?
Because I can't' see any difference between what you're saying and what I said.
What books in the line are SG-only? What books are rules books? Take the books I listed before. Can you draw a line between them?
And assuming that distinction, does the fact that a book is SG-only mean that his contents are any less explicative or and exemple of how things are supposed to work?
What I'm saying is that what's said in books is not said at random, especially on so touchy a subject. This wouldn't be the first time an exemple or a bit of text clarifies the rules, and you don't always have a clear, separate box, especially just to say "Aegides need to penetrate". Sometimes, this would be a waste of space, or less elegant, of what-have-you.
As an exemple, Legend of Hermes clarified the summoning of the dead, between rituals and formulaic spells (In the Island of Spirits chapter). Yet, this book is full of adventures, and this was done in a spell exemple, absolutely not in a box. So the clarification should be overlooked, or not taken as seriously, because it's just text in a spell description in an "adventure book"?
Here, you're basically arguing or implying that either:
- The author wrote this sentence without noticing its implications, and it was overlooked by the line editor and playtest teams as having repercussions on the line's stance. In short, it's babble, especially as it isn't enshrined in a box.
- Saying that the level AND penetration must be sufficient to stop a creature doesn't mean that the creature's might must be greater than both of them. What does it mean, then? Keep "Level AND penetration", change the sentence.
I now have a mental image of a magus skating over a magically created floor using his parma as the skates 
This I don't believe. It would mean, that you are incapable to distinguish between a text and a book. Antagonists is a book. It contains several texts. Some of these are adventures - e. g. The Waimie. But the Introduction (p.6f) is clearly not.
In the Introduction it is explicitly recommended, that each adventure text - like The Waimie - is read only by the SG in charge of that antagonist.
This implies, that that text might not be read even by the alpha SG in some campaigns - hence is not a place to put in sweeping rules clarifications.
It further determines the context in which the adventure texts are read. Hence "If the Aegis is of sufficient Level and Penetration, the covenant may end up fighting the Waimie's offspring outside the covenant." describes a problem the SG in charge of The Waimie needs to address. It does not define what "sufficient Level and Penetration" is.
Cheers
My interpretation of the RAW, with regards to the minimum level of a ritual spell, is that the sentence, "Ritual spells are always at least level 20, even if the level calculation would make them lower" means exactly what it says. The minimum level is 20. Not "minimum level plus penetration", or "minimum level plus bonuses for loud booming gestures". If your character's ReVi lab total is 24, then he cannot invent an Aegis of the Hearth without a lab text, because he has to invent at least a 20th level spell. Which, without experimentation, would take five seasons. If he experiments (and survives his sodales when they find out he experimented with an Aegis), he can cut that down to between two and four seasons, depending on the Risk Factor and how well he rolls.
I'd personally experiment with an aegis not for general use but for "Let's see what it actually does to change..."
I'm sorry Jonathan, but I really think you are the only one even thinking about including penetration in those 20 levels.
Having re-read christian's post a few times, at most I could see him talking about "maybe add a magnitude for size if you want a really big Aegis".
And since you seem to be against it, let's just forget it, yeah?
Why are you quoting Peregrine_Bjornaer and addressing me? I wasn't advocating including penetration and I thought that's what he was saying. I've long since moved passed it. The only thing I opined on was that having a HR that included penetration in the level of the spell was 1) a HR and 2) may be considered reasonable since devices do this. I'd personally never use it in a saga.