Is there any canon examples of whar happens to a Regionne if the path way to the mundane level is destroyed?
Say there is a Regionne that is in the valley of a mountain stream. Access is by walking under the waterfall in the correct direction. The Regionne resmbles the mundane geography, only more magically real (if that makes sense).
If a magus reroutes the stream, collapses the cliff responsible for the waterfall, and causes an avalanche to bury the mundane site under a dozen paces of rubble.
Would this typically affect the Regionne and its contents?
And if there is a magician left inside the Regionne, how would they get out?
Obviously, there could be previously unknown exits to be discovered.
Obviously, Divine Intervention is possible, except possibly from Infernal regione, from which God has categorically withdrawn his interest. I am not sure if the RAW statement should be read to imply «irrevocably» ...
I suppose when changes to the aura [RoP:M] create new regione, new entrances could result as well. Certainly if the aura diminishes and regio levels merge, one could find oneself at a level with an exit.
I also suppose that high level Vim spells could create or bypass exits, but an Hermetic breakthrough may be needed.
At the end of the day, it is entirely possible that there is no way to escape, because the vis/lab/arts to do high-magnitude regio manipulation simply are not there.
The typical AC to use Leap of Homecoming with is to one's lab. But using any other available AC works as well, if the regio allows it.
A tricky thing is inadvertently teleporting to a location dangerous to the magus. But those magi used to teleport a lot typically use a spell like Summoning the Distant Image on their destination before.
I think that realistically the answer is, on the one hand whatever the SG decides and on the other hand how would anyone know? Unless you are going to go around collapsing the entrances to regiones with people inside to report on the outcome... at best someone might know about one anecdotal incident that they may not know the whole story about.
I doubt there's a canon example as it would be very rare.
Very much a SG interpretation I'd say.
Is there a time lag or does the Regio change immediately with the outside?
If there is a time lag, and one exits the regio through the waterfall on the regio side, do they materialise in to solid rock?
Do regio's always have an entry and exit, and if so, does a new one get created?
The "Do arcane connection teleports work through regio's?" may have a canon answer.
Mythic Locations chapter eight has a destroyed or lost mundane entrance resulting in the regio being unaccessible until the entrance / exit is either recreated or brought back.
Additionally, I'd direct anyone interested in how regios blocking entrance interact with arcane connection effects to Thrice-Told Tales p. 19-20 Scry Beyond the Mantle and Touch the Mantle. I would infer that a regio that blocks teleport would allow a leap of homecoming to go through if you were willing to add intellego and vim requisites.
I'm pretty sure that Tablinum (Against the Dark, as referenced above) is described as having had any pathways between levels destroyed, so the only way to get to the deeper levels is through an arcane connection. However, that same section of the book has a sidebar on Leap of Homecoming and regiones which specifically says "there seems to be no reliable way to predict how a regio will interact with Rego Corpus magic."
I believe the answer is "whatever improves the stories in your saga".
So, there is no other way? Perhaps by surveying the entire boundary of the Regionne for a "weak" point, orsymbolically generating a new entrance, or flying to the top of the Regionne and transitioning to mundane sky, or so.ething else?
Heck, even getting to a hollow space in the mundane level and digging through the rubble....
There are, I think, two canon ways to create regio entrances but one is Hermetic Architecture and requires installing items on both sides and I think the other also requires being on both sides but I may be misremembering that that one exists at all and I definitely forget where it was if I am not misremembering.
EDIT: Found it, @ivgeen ! Penetrate the Regio’s Skin Cr(Re)Vi 25 (ritual) found on p99 of Mythic Locations. It does not require being cast from both sides. It is one of the relatively easily translatable Mercurian Rituals from that section of Mythic Locations.
It is not that bad a trap. We have there on p.93f:
The arch in the regio is currently standing, and the condition of the arch in the mundane world does not matter. If the arch in the regio is destroyed it is impossible to leave the regio via this exit until the arch is replaced. The aqueduct contains an alternative exit (see later) and it is possible to use Leap of Homecoming type effects to exit (or enter) the regio regardless of the condition of the arches.
Indeed. It seems like the only generic approach but to the specialist.
But you have received other suggestions too.
All of these approaches fall under the broad alternative of finding an exit previously unknown. If you can fly out of the regio, it just means that there was an exit in the sky. A weak point is just an exit, maybe one which requires elaborate action, possibly even a spell¹. Symbolically creating a new entrance also sounds like elaborate action to trigger an existing exit, depending on what you propose as you symbolic action. All of these may or may not be available in a given regio.
I think somebody posted a canon guideline to create a genuinely new exit, and there are spirits and faeries who can do that as well, if you can find one and make a bargain.
TBH, I think you are just looking for ideas for non-trivial exits ... and well, then the possibilities are endless.
¹ In a 4ed game in the last century, we ruled that we could design a custom spell to get in and out of the regio where we wanted to establish the covenant.
Another option for how the Regio is closed off is the Stasis power in RoP:M which makes the borders of the regio and entrances and exits impermeable and stops the aging of things within. In this case the exit is finding the being using that power and convincing them to let you out or to stop using their power or killing it if it won’t. In case George is right and you’re looking for story options.
Not quite. My players have occasionally derailed plots by pointing out canon stuff I have overlooked.
Hence the occasional need to sound out potential plot ideas on the forum and see how other experienced players/SGs might react. Naturally I phrase it in ways to obfuscate my intentions to my players who may be reading these forums.
(And no, I prefer not to forbid them from reading these threads. How else are the players going to learn Order of Hermes Lore)
I prefer to think of it as each regio and how they behave with things like this is distinct by canon. Even Auras are sometimes canonically distinct in ways that may affect this sort of thing. For instance the Aura in Hibernia at Qui Sonant Pro Quieto (Contested Isle p105) where no arcane connection works, including talismans and familiar bonds, within but also to and from that area unless the AC is wrapped in the Cathach of the covenant. This feature being one of the reasons the site is used as a neutral burial site for many magic-aligned things and people, so the ghosts can not be summoned with the bodies of the deceased except under allowed situation with use of the Cathach.
Side note about that canon spell I mentioned before, Penetrate the Regio's Skin, it is explicitly non-hermetic so should not be easy to invent without either the text found at the Mythic Locations site or at least a minor breakthrough to add that guideline to Hermetic Theory. With either of those options it should probably be possible to invent a different version for each of the 4 realms but, as it stands, it's something of a hole within Hermetic Theory where the effect doesn't break limits but no one knows how to do it because no one has done the work to figure out how it is done.