The Extraspatial Cube

As a delver crew grows, their wagon’s interior does, too.

What is an Extraspatial Cube? 

Not all delvers make their living in the Dungeon. Cities and curiosities were left discarded and abandoned with the sudden disappearance of the Broken World’s human denizens. As its physical laws unravel to make it more dangerous, adventurers see opportunity in its infinite detritus. 

A valuable export of Broken World scavengers is its physical space. With clever containment magic, a scavenger can carve out a cube of Broken World there-ness, drop it in a wooden crate, and carry it back to the Beast World. These scavengers then sell the box of space to those looking for extra (and efficient) living space. 

How to Use a Cube 

An unused extraspatial cube is a wooden crate, which is nailed shut and stamped with the symbol of an impossible cube. After speaking the command word, the crate can be pried open to expand a closed volume. Placement of the extra space must be designated when the crate is opened, and the extra space remains the same shape within its new home: a cube exactly 5 feet on a side (“designer cubes” in unusual shapes can be commissioned, but their bespoke nature triples the cost). 

The magic of the cube stretches the container of the expanded volume, but only on the inside. Therefore, a cube emptied into a wagon’s new crawl space also warps the timber of its walls. The wizards who solved the magic of extraspatial cubes named this phenomenon “Making it Make Sense.” 

The Rules of Space 

Extraspatial cubes are such a commercial hit because of how safe and stable they are. As long as a user follows some basic rules, a cube makes an effort to remain inside its new volume. 

#1: The Rule of Egress.

The exits of an extraspatial volume must be in the same relative position inside and out. This is known as the Rule of Egress. But what does this mean? 
First, it means the inside of your wagon can’t have more windows, doors, hatches, or other means of egress than the outside. If two windows look outside, the outside has two windows. 
Second, windows and doors must be in the same relative position to each other on either side. A window to the east of another is to the east on both sides. You may need to walk half a mile indoors between windows only 5 feet apart outside. However, you walk the same direction either way. A cube stretches space, but doesn’t twist it. 

#2: The Rule of Orientation. 

This rule follows from the first—if a door faces west on the inside, it must also face west on the outside. A body can’t rotate by traveling through a portal. 
This is easier to explain visually. The diagram is an example of a wagon with extra space. The windows, door, and hatch are all in the same direction from each other inside and out. Looking through window 1 from the outside sees straight through window 3, but the windows don’t cross such that movement would be mirrored if you passed through both. 

#3: The Rule of Five Faces.

As long as five enclosing faces of a volume are intact, its extraspatial cubes remain. In short, if one wall falls down, your stuff won’t suddenly pop out. 
From the outside, extra space can look strange, to say the least. Different observers see it in different ways. Some describe a stretched or shrunken image within. Others report a “doubling effect,” with space overlapping within a volume. Either way, passing the enclosing volume’s threshold normalizes perception, and nothing is ever made invisible to the outside by being in extra space. 

#4: The Rule of Influence. 

Any force applied to the outside applies to the inside, and vice versa. A wagon is the weight of everything inside it, even in extra space. This also means if a wagon tips over, everything inside also tumbles. 

#5: The Rule of Decreasing Elasticity. 

The more extra space a natural volume has, the more difficult it is to expand. While the School of Space Wizards hasn’t discovered the breaking point of a physical volume yet, the effort necessary to add cubes to a room increases every time one is added. Put simply: cubes cost more the more you add.

#6: The Rule of Mundaneness. 

Ongoing magic can’t be the source of an item sold as an extraspatial cube. In other words, the added space is not magic. It’s a byproduct of the Broken World’s extraordinary physical laws, packed up and brought to the Beast World. This means that a bigger-on-the-inside space can pass through an antimagic field without worry. Extra space can’t be dispelled or affected by a bag of holding or portable hole. 

#7: The Rule of Preservation of Existence 

Spoilsports consider this “the most important rule”: the failure of an extraspatial cube can never affect the existence of its contents. 
When the Rule of Five Faces is broken (i.e., a building with cubes is razed), the contents of extraspatial cubes appear in the nearest unoccupied natural space. The cubes are lost, spreading out infinitely to make the general “outside” just a little bit bigger. 

An Example of Bad Planning 


In the diagram below, we see an example of a dream house that can’t exist. Here are just a few of its many embarrassing problems: 
  1. Door 1 faces different directions on the inside and out. Looking through it would bend one’s perception 90 degrees. This is preposterous! 
  2. As with the door, window 2 faces a completely opposite direction inside and out. Moving south through it from the inside would be moving north through it from the outside. Again, laughable. 
  3. Window 3 only exists on the inside. What are you looking at when you peek through it? This is like a child’s drawing. 
  4. This problem is more subtle—the roof hatch is south of window 1 on the outside, but north of window 1 on the inside. If this were the only problem, the fiction of this schematic would still be obvious. 

Cube Prices 

The cost to add an extraspatial cube depends on how many are already inside. Every crate has a number on it, signifying how many can already exist in the volume it is added to. The current market prices are as follows; budget accordingly. 


Cube Prices
Cubes Already Present - Price Per Cube (gp)0-2 - 2003-8 - 800
9-20 - 320021-40 - 1280041+ - 51200