LoH, p.123 "A note on Boundary effects" claims that T:Bound effects do not move if the "physical anchor" of the Boundary moves (and thus, implicitly, that they do not vanish if a Boundary vanishes).
TMRE, p.74 "The Haunt [of the Living Ghost]" seems to contradict this: boundary effects keep aligned with the "physical anchor" of the boundary if it shifts, contracts, or expands, and cease if it is destroyed.
I think that the corebook should clarify upfront which of the two views is correct, and the incorrect one in LoH/TMRE should be addressed in the errata. (Personally, I think that the LoH one should be errata'd: it does not fit the mythic aesthetics, and it opens all kinds of cans of worms. I am far from alone in this view: I am sure @Ovarwa can be far more persuasive than I am on the matter.)
LoH p.123 box A Note on Boundary Effects is an explicit clarification of T: Boundary. It keeps T: Boundary simple and a classical type of Target.
TMRE p.73 The Haunt causes serious problems not only with T: Boundary, but also with T: Room and T: Structure, if understood as a general example, how these targets work. There is also no reason to understand it that way.
In which saga a T: Room D: Sun Curse of Circe can be dispelled by demolishing the room the target persons were in at casting time? Could these just leave the room and were thereby no longer affected by the Curse?
Quite the opposite. LoH view becomes completely nonsensical if applied to T:Structure. If I cast a D:Sun spell on a ship (T:Structure), I fully expect it to move with the ship, if the ship moves -- not to be left behind!
I'm not a fan of the sidebar on Boundary targets, with the notion of a floating aegis once the flying castle starts moving again. Also, bear in mind that enchanting a ship with structure-level enchantments is one of the example uses of Hermetic Architecture in TMRE, and Memnos of Favonius does exactly this in TSE. Applying that sidebar to Room and structure targets would be a problem. And yet, the three targets should work in similar ways in theory.
Right, it was you who just brought the issue up You said that the spell-moves-with-Target view "causes serious problems not only to T:Boundary, but also with T: Room and T: Structure, if understood as a general example, how these targets work.".
Ok, let me make a proposal: we have stated our views. Should we stop here, allow everyone else who wants to make one post on the subject, and wait until David Chart opens a thread (as he did with Elementalism, T:Circle etc.) to go all in? The ArM5 errata is really, really long, and I don't want to derail it too much.
That has nothing to do with a generic spell-moves-with-target view.
EDIT: The Target parameter of a spell in general defines, what is affected by it.
If a T: Structure of a Herbam spell is made of wood, that spell can very well affect the entire structure, and its effect move with it.
If the T: Room of a Corpus spell is just a hut, that spell affects all the people within it. The spell effect moves then with the enspelled people.
Moving or destroying the hut after the spell took effect should not dispel its effect on these people.
I think that's an excellent suggestion, thank you. I quite agree with you about the original thread. So, all moved here. Please discuss freely. I agree that something needs to be done here, and input on what is welcome.
My point here was that, with a flying castle, you could cast an aegis, then move the castle. With the logic of that sidebar, you would now have a pocket aegis flying in the air. For added fun, you stop your castle again to recast an aegis and you have a second flying aegis bubble adjacent to the first. Do that a few times, and you can surround the mountain where that pesky dragon clan was flying from, and so long as they were sleeping through your rituals, they can now spend the year starving or sleeping. Or we can do this in the middle of a featureless plain, plan a wizard's war there for "fairness", and laugh it off when the poor enemy realises there's a non-covenant stopping his spells. On the upside of having a Compass for portable aegis installation midair (tm), we've balanced flying castles and sailing ships. No aegis for you. Burn down at the first sign of a Ball of Abysmal Flame, Favonius, Northern Seas. Teach you a lesson for wanting a fun covenant that would generate stories by sailing arround - please make sure to spend all your seasons crafting variant spell defenses to cover your lack of an aegis. Get a static covenant next time!
On a less satirical tone, in my game, an aegis stays where it was cast, even if the boundary moves. Destroying the outer wall to breach a boundary isn't a problem until the next aegis, and favonius ships can have an aegis since a structure is smaller than a boundary but still has a defined boundary. The Aegis stays with the ship as it sails. Yes, it protects the ship from small naval monsters. If the flying castle comes up in my game and I need an explanation for why there was no aegis, It'll be very simple, a mix of overconfidence and lack of vim vis income led the magi to prioritize his resources elsewhere.
So with me noting that I totally like this idea and would implement it myself - I didn't think you could change Aegis from Boundary to Structure.
That said, I totally like the idea that you can and thus you can have it be applied to something that moves and so the Aegis moves with the target. No I am imagining a roaming band of magi living in nicely furnished wagons that each have the aegis on it. hehe
Also, one way to explain how the Thomae city didn't have it is that the aegis being able to be Structure wasn't developed till after the city was built.
You shouldn't be able to change the Aegis from Boundary to Structure, by RAW. Actually my approach doesn't. Since boats also fit the definition of a well-defined man-made boundary, the boundary target applies. What you don't get to do is save on a level of magnitude by changing it to "structure". The next step is ignoring the sidebox that says boundaries can't move. That is really where the house rule is.
I think this post of OneShot is a good starting point to look at Boundary in the broader context of spells targeting a "place" (T:Circle, T:Room, T:Structure and T:Boundary) with a Duration longer than Momentary. The crux of the problem is: what happens if, after the casting, the place and/or its contents move?
There are basically three different ways in which ArM5 treats these spells, one unique to the Thomae's chapter in Legends of Hermes (and T:Boundary), and two common across books and Targets. I'll illustrate all three with OneShot's example of a T:Room D:Sun Curse of Circe, that turns people in a Room (let's say, a tent) into hogs.
the magic remains fixed in space. This is how LoH answers the question: if you cast an Aegis on the island of Delos, when the island moves a Delos-shaped patch of Aegis is left in the middle of the Aegean Sea (and Delos is no longer protected).
To go with OneShot's example: a D:Sun T:Room Curse of Circe, that is cast on a tent, remains fixed in space when the tent is moved or dismantled. Until the next sunrise/sunset anyone entering the area where the tent was, gets transformed into a hog, but reverts to a human as soon as he leaves that area. If the tent is on a cart moving in circles, people staying in the tent periodically turn into hogs (when the cart reenters the original casting area) and then back to humans (when the carts leaves the area).
the magic is attached to the place. This becomes different from 1. only if the place can move, or can cease to exist; so for a lot of spells like The Shrouded Glen it could be either way -- it's not clear from the description. It's explicit (for T:Room, Structure, and Bound) in the case of the Living Ghost's Haunt from TMRE. It's also obviously the case for non-momentary spells that affect the contents of ships, such as the T:Room Ward the Drowning Waves from MoH.
To go with OneShot's example, a D:Sun T:Room Curse of Circe cast on a tent, for the spell's duration anyone entering the tent is turned into a hog, and remains a hog until leaving the tent. This remains true even if the tent is moved around on a cart. If the tent is destroyed, the spell ceases.
the magic is attached to the contents. The place is relevant only at casting time: those in the place at that time, are affected for the entire duration, no matter what they do afterwards. Those not in the place at casting time are never affected, no matter what they do afterwards. One such effect from the corebook is Incantation of Putrid Wine.
To go with OneShot's example, a D:Sun T:Room Curse of Circe cast on a tent, then the unfortunate victims can leave the room but will stay as hogs until the next sunrise/set -- conversely, people who enter the room after casting are unaffected.
Ideally, only one of 1,2,3 would be valid for all "place" targets. This would be simple and clear all arguments.
Unfortunately, I think that 2 and 3 are too widespread over all books (and over all Targets) for one of them to disappear. Also, they are both common in folktales. So we probably have to live with the idea that whoever designs a spell can choose between 2 and 3 (at a minumum), at least for some Targets. Saying that 2 and 3 are infeasible only for T:Bound, as LoH, just creates a mess in my view -- and negates some very valid sagas that people are running, based on ships, moving islands (like Delos), and cloud-top castles.
Should we allow the spell designer to also choose 1? Keep in mind that the only reason 1 was introduced was to explicitly forbid 2 & 3, not to allow some interesting and "appropriately mythic" application of 1. And frankly, I cannot imagine any such application. So, since if you allow Boundaries of type 2 & 3 to exist you remove all existing reasons LoH's insert, I'd just disallow 1 across the entire Target spectrum (changing the LoH insert into something like "The mystery of the missing Aegis").
You are aware that I could just say: yes, good that we agree!
Yep. Just as you inadvertently said above. Of course, casting that Aegis takes at least an hour, during which its Boundary must not move or waver, and it also takes at least 4 pawns of Vis. If there is the chance of change in the Boundary during casting, the SG is entitled to request a stress roll even if the caster has mastered the Aegis. If there is a change, the casting fails and might botch.
So casting lots of Aegides "just because" is a troublesome and expensive fool's errand. All the benefits of success would also depend on Aegides stretching out to the lunar sphere - an unlikely house rule.
You need to have a rule, what happens to an Aegis - or any T: Boundary effect - cast, once that Boundary gets tampered with. The generic rule is, that a Target parameter no longer matters, after casting is done. All that remains are the beings or objects affected by the spell for its Duration. There are no exceptions - like those for T: Circle - described under ArM5 p.111f Spell Design for T: Boundary, T: Structure or T: Room. LoH p.123 box A Note on Boundary Effects just spells this out clearly.
EDIT: As is spelled out in ArM5 p.114 Magical Wards, their "target is the thing protected", and in case of T: Circle wards the inside and outside of the Circle from effects from the other side. The T: Boundary Aegis is a modified extension of Magical Wards, also protecting the area inside the Boundary.
I'm up for 2, in that something like an Aegis will stay with the moving structure or castle or something. I find that this opens up more things then it closes and to me that is where the benefit is.
I mean if you had a saga where the player magi have a covenant on a boat then saying 'your boat has an aegis' just works with the game and the intentions of the players and thus is maximal fun for everyone. WHY make it more annoying than it needs to be by saying "sorry, nope, no aegis for you!"
One could also solve the Thomae Castle problem by saying 'It did have an aegis, but the griffons that destroyed it just so happened to hatch there and so were considered as part of the wards when the next casting occurred."
The spell's Target parameter is one aspect of its targets. Its Form is another, that is equally important. Rarely T: Room, T: Structure and T: Boundary spells target all of a place - most of the time they target specific types of beings, things and general stuff in a place. Wards and the Aegis are rather an exception here, treated by the Magical Wards chapter and the Aegis description of ArM5.
You can't without a house rule or at least a Major Breakthrough (see ArM5 p.161 last paragraph). But if an Aegis for your ship is of utmost important for your saga, such a Breakthrough could in your saga well have already been accomplished by a follower of Notatus.
Such a breakthough better be kept secret in a small cabal! Movable Aegides in general can also revolutionize magical warfare by siege towers, assault ships, flying fortresses (with magical bombs!) and magical digging machines protected by such Aegides!
You said that the spell-moves-with-Target view "causes serious problems not only to T:Boundary, but also with T: Room and T: Structure, if understood as a general example, how these targets work.".