Playing with Extradimensional Spaces

Here we have another question from Alzrius…

The Practical Enchanter offers some great spells for creating extradimensional spaces, but what about ways to manipulate such spaces (though this borders on planar travel in some areas)? How do I break into someone else’s extradimensional space, or ward them from breaking into mine? How can I take something in the real world and shunt it into a personal extradimensional space or demiplane? How would I force something in an extradimensional space or demiplane back into the real world? Would size be a factor (e.g. a demiplane the size of a continent or world that I wanted to merge with my native world)?

This particular group of questions mostly calls for secondary effects.

Breaking into a plane physically requires an open gate of some sort; otherwise there simply isn’t anywhere to apply physical force to it. A long-term extra-dimensional space can simply be fitted with physical defenses around it’s gate (for an example, see Realmsong). If you want to put in – say – iron-reinforced doors and a selection of traps to hide behind, you want the “Trapped” modifier (and possibly “Furnished” in case you want to hide the traps and have nicer doors) from the modifier listing in The Practical Enchanter.

That, of course, suggests an interesting combination spell – an illusion-and-spacewarp which creates a spacewarp full of traps and barriers with an illusion that makes it look like you opened a door and fled into the space while covering up the fact that you actually opened the door in front of yourself.

The easy way around people breaking in physically is to simply close the portal. You can do that with the “Barriers” modifier, which allows you to open and close the gate at will. A closed gate is pretty much proof against physical force – save, perhaps, for some epic-level use of Open Lock or Escape Artist. (If you can use Escape Artist to get through a Wall of Force, I don’t see why you can’t use it to pass through other walls or sealed gates). Such a gate could be tricked into opening if the effect exists as an independent mechanism built into a continuing spell, employing the Use Magic Device skill or a specialized spell to impersonate the caster.

It could also be forced via a Gate Keying effect (those are usually level two for gates that are just shut or level three for gates that have special conditions on them – plus any gyrations you have to go through in the case of gates that have wards or seals on them). Spells like that are relatively uncommon in most d20 games, but probably shouldn’t be; getting into mystical locations that were sealed away centuries ago or where the local yokels cannot reach is a staple of fantasy fiction – and provides a wonderfully simple answer for “why those horrific monsters aren’t out ravishing the area”; they’re all sealed away because they can’t cast the right spells. They’re fun in gate-network games too.

Finally, gates which are actively linked to their creators can be opened by applying some method of taking control of the spell away from the caster.  That’s vanishingly rare in most games, and with good reason; it’s a great deal more complicated than simply forcing the gate open – usually even more complicated than a planar travel spell that doesn’t even need a gate – and how often do you want long-term control of someone else’s portal? The vast majority of the time, a far simpler and easier Gate Keying effect will do everything you need.

To get around the problem of people seizing control of your gate, you’ll either want internal defenses (as above) or to apply some reasonable level of the Mobile modifier: moving your entryway into a co-existent plane, or a hundred feet underground, or some such, will prevent anyone from using it who isn’t willing to invest a great deal of power in the project.

To prevent people from planeshifting into your extradimensional space without your permission requires a second level of the Barrier modifier; it blocks anything short of Wish, Miracle, Divine Intervention, or those specific “seize control of the portal” spells from accessing your dimension. It might be a reasonable extension to allow another +2 levels or so to block anything short of a specifically-developed epic spell, but that probably isn’t worth the bother unless you desperately want to seal something up for some approximation of “forever”.

Moving things in and out of an interdimensional space is another matter altogether.

If you want to drag something out of a pocket dimension back into reality, there are three basic approaches;

  • You can collapse the pocket dimension, so that the stuff in it drops back into some other plane.
  • You can (or perhaps a minion) go in and carry or plane shift it out.
  • You can send in something a spell or power to latch on to whatever-it-is and drag it back.

The first is straightforward, if magically expensive; you can power up a transdimensional dispelling effect, or send in a minion to do something catastrophic – probably the old “extradimensional space in an extradimensional space” routine – to destroy the place. This usually works, but doesn’t really guarantee that the things you actually wanted will wind up anywhere near you.

Going or sending in a minion is easiest to describe; it doesn’t even necessarily require any magic or special powers – although it can be a difficult and dangerous trip.

Latching on to something in an extradimensional space and dragging it back is harder; basically what you want there is a Plane Shift with transdimensional range on it and some method of targeting it. Size would be a factor; if the thing you want is very large, you’re going to want to bump up the area affected as well. The metamagics in Eclipse can do all that, but it’s going to be expensive on more than one level.

Alternatively, you may be able to get away with Conjuration. After all, if a mere first-level spell can reach across the dimensions, grab a creature, drag it to you, compel it’s obedience, and then send it back home regardless of intervening barriers, you might be able to conjure something out of a pocket dimension a lot more easily – but if you’re using my far more limited interpretation of how summoning spells work from The Practical Enchanter, than this won’t work.

Personally, unless a character has access to high-powered freeform magic, and is willing to use a lot of it, I’d go with Ceremonial or Ritual Magic; it’s a lot easier to work up once-off effects that way.

Finally, we have merging a demiplane or continent into another world.

That’s… awkward.

  • What set of natural laws or planar traits is it going to work under? World A? World B? Both at once? A merged or compromise set? Which will dominate? Are we revising two entire universes here?
  • Are the contents of a pocket realm simply going to be dumped on top of whatever’s there now? That could be a pretty major disaster, and will probably convert whatever is in the pocket realm into a huge pile of junk.
  • Is it going to merge with what’s there now? That’s going to be really complicated when it comes to the people and creatures.
  • If it displaces what’s there now, where is the stuff it displaces going to go? Will there be tidal waves, a fantastic impact, and other disasters? What will crossing over the border be like?
  • Will it distort the local geometry to make space, packing an area of – perhaps – immense size into an area that can easily be walked around in a few moments?
  • Is it going to manifest as a co-existent plane that’s really easy to see into and shift back and forth into? That’s a simple idea, and avoids a lot of other problems, but adding a new dimension of movement to the game will complicate other things tremendously.
  • Will there be limited access-ways? Perhaps few walls, or narrow mountain passes, that lead to the newly-added areas? That’s pretty much just adding some permanent gates to the world.

In theory, a sufficiently high-level spell could simply drop a pocket dimension into a larger world in the form of a new planet – either transforming it to work under the rules of it’s new dimension or altering those rules locally. A demon-lord who rolls up his hell-dimension into a new “planet” and brings his entire power-base along for an invasion would certainly make an epic villain.

The trouble with this is that there are simply too many undefined parameters to say much that’s meaningful about the magics involved – although we can be sure that they’re going to have to affect a massive area and will be extremely high level. For the most part, however, we’d simply be looking at a planetary-scale instantaneous gate or overlay; that would cover the overlay, limited-access, and spatial-distortion variants – and could even cover an exchange-variant of the “displacement” version. The merger effect however… that calls for a massive transdimensional transformation capable of affecting multiple worlds.

On the other hand, events on this scale will often fall into the “Plot Device” category. Ergo, once again, the best option is Ceremonial or Ritual Magic.

Legends of High Fantasy – with it’s drastically expanded ritual magic system – even included a ritual for this sort of stunt.

Budding the World Tree: Stabilizes areas of the dimensional fringe of Cemar, possibly even adding substantial amounts of territory to the world. In general, one can attempt to stabilize a route, to stabilize several routes – or to push back the fringes entirely. The rite always involves planting a twig which grows into a mighty tree during the rite; while it endures it’s roots and branches will hold reality steady, as will any offspring after it. Destroying such a tree, grove, or forest, will allow the lands they held to fade into the mists once more. In general, Area (Route +10, Routes +15, Domain +20), Eons (+20), Severe (+10) and Target Present (-) = DC 40 (Route), 45 (Routes), or 50 (Realm). There are several minor artifacts which can help with this sort of rite, but the components are difficult to come by. Still, creating a stable route to any other world offers enough possibilities for wealth for people to keep trying.

  • This ritual is commonly used by Sorcerers and Wizards.
  • Lesser rituals can stabilize a route long enough for an expedition but if you’re still away when the rite expires – or is disrupted – you’ll likely never return.

The Practical Enchanter can be found in a Print Edition (Lulu), an Electronic Edition (RPGNow), and a Shareware Edition (RPGNow).  There’s an RPGNow Staff Review too. Eclipse: The Codex Persona is available in a Freeware PDF Version, in Print, and in a Paid PDF Version that includes Eclipse II (245 pages of Eclipse races, character and power builds, items, relics, martial arts, and other material) and the web expansion. It will be updated with Eclipse III when that’s done as well.


3 Responses

  1. another interesting option for limiting access to your pocket dimension would be to make a spell that creates 2 pocket dimensions that have gates that can be opened and closed in the same place (only one open at a time)… one with traps and one with say a nice room for rest and recovery. … how anoying would that be to build? does it need stable on one of them to make it work?

    • Hm. Missed this one… If you’re overlapping the gates, even if only one is open at a time, you’d want “Stable” on both of them.

  2. […] or possibly for a Ward Major (also discussed in The Practical Enchanter) and is discussed further in Playing with Extradimensional Spaces. There also may be some useful bits in THIS article on magical creating cities. The Genesis spell / […]

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