How to I symbolize the damage to reality from a planar incursion?

[ldvhl]

In the backstory to the campaign I'm developing, a big demon from the Demiplane of Shadow ripped open the barriers between the Prime Material and his plane and tried to pull the world into the plane. A new god was born, fought off the incursion, etc. etc. However, there are leftovers from the invasion, even an entire Age of history later. I was thinking of using a re-colored vector image of a laceration to depict the areas sill "wounded" by the invasion, but I was wondering if other folks might have better ideas?

Thank you!

[Redrobes]

A problem with all maps depicting events that occur around an extra planar events is that by nature of them being on a different plane one has to come up with a way to map what is in another dimension onto the 3 dimensional world that exists. Of course we plot 3 dimensional worlds onto 2D bits of paper and image by the use of a projection. It took some smart people to work out these projections like Mercator etc. So what you might do to project extra dimensional things is up for grabs.

The old Dungeon Masters Guide and associated books had diagrams that showed lots of 2D squares layered up with Astral planes etc floating about in a wishy washy sort of way that kind of worked and gave the general impression. I think the Norse people had their Valhalla, Asgard and so on as parts of a tree - a tree of life.

Its going to need some similar creativity to express how you want to show it but I think it will be interesting and I hope you upload the image of what you come up with. But I think there is no definitive answer here and wild and outrageous ideas are all game.

[ldvhl]

I remember the old DMG graphics, I'll have to take another look at those. Thanks for the reminder. There were some tesseracts in there somewhere too but I don't think I'm up for that sort of challenge.

Guess it's time for the brain to do some work.

[Caenwyr]

This is essentially an exercise in higher dimensions. The easy way to think this through is by removing one (or more) dimensions from the equation. It's impossible for the human mind to imagine two three-dimensional worlds intersecting, but if you reduce it for a second to two dimensions, the problem becomes almost trivial.

Take two sheets of (two-dimensional) paper, both extending infinitely in two directions. We'll call them planes. Assuming both are perfectly flat (and they are, otherwise they wouldn't be two-dimensional... but I'll get back to that!), these planes, when placed in different locations within a three-dimensional universe, can be either perfectly parallel to one another, in which case they will never touch or, if there is even the slightest angle between the two they will at some point intersect.

And this is where the cool stuff begins. Because this intersection (again assuming both planes are flat) will take the form of an infinitely long, perfectly straight line. Depending on your personal preference, you could consider this line:

• an impenetrable barrier (essentially cutting each plane in half, causing 2D creatures on one sides to be unable to cross to the other),
• a permeable barrier that will allow 2D creatures to get a fleeting glimpse of another plane as they travel across it without them being able to travel to it,
• a portal that will allow the creature to "hop" onto the other plane OR continue moving on its own plane, depending on what they want, or finally
• a portal that will take the 2D creature to the other plane every time they cross it (meaning the creature would have to step through the portal, arrive into the other plane, turn around and step through the portal again for it to arrive on the other half of its original plane). The creature would have to step through the same portal 4 times to arrive on the same side of the same plane again, precisely where it started.

You could play with the nature of this barrier/portal or have it fluctuate over time to give your 2D creatures some excitement. Who knows where they'll end up!

But it gets better (or worse). The planes don't *have* to be flat in the three-dimensional space for them to be *perceived* flat by their inhabitants. In fact, 2D creatures will happily travel along them, oblivious to the shape of their 2D world in a 3D universe, even if in fact the planes are bumpy or wavy. This means that the planes might touch in several places at once. Each barrier/portal would have to be either "infinite" (stretching from one end of both 2D worlds to the other) or "closed" (imagine a hill in one plane poking through a flat section in the other plane: the resulting section will be circular. Or any shape a line could take that ends where it begins). This means that there could be portals anywhere, not just along one axis. And some portals would be so small that you could walk around them instead of stepping through them.

Okay, time to scale this idea up one dimension. Imagine two three-dimensional worlds intersecting. You can't visualize this anymore, but looking back at the paragraphs above will help you theorize the effects. Assuming both worlds are "flat" in the 4D universe, they will intersect along precisely one, infinitely tall and wide, infinitely thin 2D plane. The easiest way to imagine this is a shimmering wall cutting all the way through space, possibly going straight through a planet (the planet where your protagonist lives?). Your protagonist could then walk up to that wall and step through, ending up on the other 3D world (people tend to call these worlds "planes", but in reality they're actually infinitely large 3D "volumes"). If this evil god person created a rift between the worlds, this could be interpreted as taking one 3D "volume" and moving/rotating it through 4D hyperspace in such a way that it was no longer parallel to the other one but intersected with it. He could even pick the exact planes in both worlds along which they would intersect (assuming this god has access to enough energy to shuffle about entire 3D universes through 4D hyperspace).

Or, if both 3D worlds are *not* flat but bumpy, intersecting them would cause several planes to appear, some wavy but infinitely tall and wide, others limited in size but closed, like bubbles. These bubbles are especially interesting. They too would act as a portal, just like the flat one would from the previous paragraph, but they could be as large or as small as you want: big enough to encapsulate entire planets, so small that they're invisible to the naked eye. Imagine a bubble opening up in your town centre that corresponds with a bubble 10 miles deep within an ocean in the other world. Imagine the enormous pressure with which the ocean water would start spraying - and keep spraying! - until hydrostatic pressure on both sides was in equilibrium again (which will only happen once the water is equally deep on both sides so... a very long time indeed). Or a bubble opening up to empty interstellar space. Yikes.

Getting back to your question: a god ripping open a rift would mean they somehow intersected the Demiplane of Shadow with the Prime Material. As long as both "planes" (in reality "volumes") remain in their new location within 4D hyperspace, the intersection(s) will remain in place too, with all sorts of physical effects like the two I described above (there are plenty more I can think of by the way!). In order to "close" this rift, one would have to move both worlds apart enough for them to no longer intersect. It would again take godlike powers to perform this particular magic trick, but it seems you have this covered. The fun thing is, along the fringes of what used to be the rift plane(s), you'd still see the scars from all those physical effects: that town with the bubble connecting it to that super deep ocean? It would be completely destroyed in the event, and if it took long enough to close the bubble, the entire surroundings would be washed away with such force that it could be compared to a Missoula Flood event, with massive canyons eroded not over a timespan of millions of years but days, but in this case without there being any indication of where the water came from once the bubble closes. And again, this is just one example of how a rift between worlds could create lasting effects on the world.

You know, I've been thinking this through for the better part of an hour now — I think I'm gonna make a map (or build a world!) with precisely this premise. Is that okay? No gods or anything in my interpretation, I like my physics to be weird but plausible. So I don't think I'll interfere with your idea. It's too much fun just to leave it lying around. But you can employ it for your world too if you want! No copyright, do with it what you will. Ain't I gracious today .

[ldvhl]

Dude Caenwyr that's a lot. I appreciate it, there's a lot to chew on there. I might have to work on some other maps while I let that stew. I also look forward to seeing what you come up with!