Plane of Phlogiston

It is the river that flows to other worlds.
It is the road to other realms.
It is the ocean that links the seas of night.

    Outside and between the crystal spheres is a turbulent, rainbow ocean of flammable ether called the phlogiston. The multicolored sea that is the phlogiston is a transitive plane which float the various crystal spheres (and their systems within), which are alternate prime material planes with a finite dimension that are vast in size. (Not all prime material planes are finite nor are they connected to the phlogiston). The term phlogiston is applied equally to both the multicolored medium and to the entire region surrounding the crystal spheres.
    Phlogiston has varying thickness in space and forms dense rivers between the planet-sized objects (such as the spheres themselves). Voyagers moving along these paths of concentrated phlogiston discover that the greater the density of the flow, the faster the ship can move. A ship can speed up and slow down by penetrating deeper into or raising itself out of these phlogiston rivers. Stellar distances can be covered quickly in such areas. Further, the speed of the ship is at least partially dependent on the surface area it presents to the flow, so many ships carry sails to increase their speed in the interstellar ocean.

Plane of Phlogiston Traits
The Plane of Phlogiston is a transitive plane that is coterminous with the Material and Alternate Material Planes. It has the following traits:

&   No Gravity:
Technically, there are few, if any, celestial bodies in the Plane of Phlogiston large enough to create the gravity found on worlds like Oerth and Toril. Magic and advanced technology that duplicates the effects of gravity will work normally on this plane. For the most part, visitors to the Plane of Phlogiston and the craft they bring are suspended in zero gravity, so they will require some form of motive power.
&   Normal Time.  
&   Infinite Size  
&   Alterable Morphic:
There is little on this plane to alter however, objects found on this plane can be altered. The wisp of the phlogiston itself cannot be shaped or contained with out the use of magic.
&   Enhanced Magic:
Spells and spell-like abilities with the fire descriptor are enpowered, maximized and widened (as if the Maximize Spell and Widen Spell feats were used on them, but the spells don’t require extra spell-slots or additional preparation). Thus, a fireball spell will inflict maximum damage plus an additional 50% more damage as determined by rolling damage with increased area of effect. Additionally, fire-based spells and spell-like abilities always have a range of Personal. Remember that two doublings equals a tripling, and so forth.

Features of the Phlogiston
    Phlogiston is none of the recognized four elemental matters. It is neither air, nor earth, fire nor water. It cannot be reproduced or brought inside the bounds of a crystal sphere. If an attempt is made, whether by physical or magical containment, the phlogiston inexplicably dissipates, leaving no trace. Phlogiston simply cannot exist within wildspace or on the surface of a planet.
    Finally, phlogiston is dangerously flammable, much like oil-soaked cotton, which poses its own problems. Any flame exposed to phlogiston causes the surrounding area (including the phlogiston laden air envelope of the ship) to burst into flame, it is for this reason that bombards, arquebus, and any other weapons, which rely on a spark or the flame, are not used in the phlogiston. The effects of magical fire descriptor spells have been covered earlier; the effects of non-magical effects of various types of flame exposed to phlogiston are as follows:

Match (fuse)   1d2 fireball in a 2-inch diameter sphere (plus immediate misfire if arquebus)
Candle (lit)   1d6 fireball in a 4-inch diameter sphere (enough to engulf a persons hand)
Lantern (lit)   3d6 fireball in a 1-foot diameter sphere
Oil Flask (lit)   3d6 fireball in a 3-foot diameter sphere
Cooking Fire   4d6 fireball that is 5-feet in radius

    These effects occur immediately. For example, lighting a flask of oil to use as an incendiary weapon will cause it to explode immediately. Actually, a character would have to be extremely tricky and careful even to get that far. The phlogiston would ignite as soon as a flame was created with which to ignite the oil.
    Because of the nature of phlogiston, the crew extinguishes all flaming light sources before entering the flow. Phlogiston is radiant, so no other lights are needed on the exposed decks. Below decks, or in rare (and haunted) Dark Regions of space, cold natural lights (moths or fireflies, fluorescent moss) or magical lights are used for illumination. The heart of the dwarven mountain-craft is without running lights, since dwarves have infravision.
    Voyagers can move along the rivers of phlogiston at random or according to planned course. Many of these rivers flow in both directions between two crystal spheres. In some cases, a river flows in one direction only, forcing the voyager to follow a different course when returning home.
    The crystal spheres bob in the phlogiston like corks in an ocean (mind boggling, enormous corks, but they do bob). As a result, over time the spheres actually shift their positions relative to each other. This almost never changes the courses of the rivers, however, so navigation is possible. But just because a ship passed certain landmarks on its way from A to B does not mean the ship will pass those same landmarks on its way back to A from B. Fortunately, when crystal spheres drift too close, the phlogiston between them thickens to the point where the two massive spheres are moved apart and a collision is prevented.
    Navigation charts of phlogiston show the major channels of flow between the spheres. Arrows in opposite directions on the map show, two-way flow. A single arrow shows flow in only one direction.

Phlogiston Links
    The phlogiston only connects to prime material plans and alternate prime material planes (each inhabitant of an alternate prime material plane sees his or her prime material plane as the Prime Material Plane and all other to alternate prime material planes), if the phlogiston links to any other planes it is unknown at this time.
    As the phlogiston is only a coterminous transitive plane it meets the prime material plane at a point called the Crystal Sphere. Crystal spheres or crystal shells bound all wildspace. Inside the crystal sphere is the vacuum of wildspace, the planets, and stars that composes the total of a particular prime material. The spheres consist of an unbreakable, dark, ceramic material of unknown origin and have no gravity along either their interior or exterior sides (an exception to the rule that all large objects have gravity). No magic has been found that can damage or alter the surface of a sphere, except for those spells, which cause portals to open.
    It is these portals that allow spelljamming ships to pass from the vastness of wildspace into the phlogiston. Some times the portal seem to create themselves only to collapse a short time latter. These portals can range from 100 feet in diameter to up to a half-mile in diameter typical and maybe even larger! (Reports of size class A planets passing thru naturally occurring portals.)

Phlogiston Inhabitants
    At first one could not imagine any native life forms that would or could exist in the phlogiston but there are many creatures to be found here included the following: Ancient Mariner, Delphinid, Ephemeral, Flowfiend, Lumineaux, Pristatic and the Survivor. Other than the delphinid, sailors would rather not encounter any other denizens of the phlogiston.
    Naturally one would expect to encounter ships that ply the rainbow ocean of the phlogiston to get from one crystal sphere to another.

Movement and Combat
    Movement in the phlogiston is at the mercy of the flow itself. The smaller the area of object/creature the flow 'pushes' against the slower it goes, it is for this reason that ships with sails are favored over ships without sails.
    In general, it takes from 15-150 days to travel from one crystal sphere to another for ships without sails. Ships with sails take 10-100 days and those that are topped out take only 5-50 days! The sphere reached is random unless a locator device is used to find a particular sphere. These locators, supplied by the Mercane or duplicated by spells, target the particular sphere that is sought. Some spheres are unreachable from others due to the Flow itself, and travelers must go through a third or fourth sphere in order to reach their goal. These anomalies are noted under the individual spheres-which spheres are nearby and can be reached regularly, and which ones are not. Some spheres drift into and out of proximity with each other, so that just because you reach an area once does not mean that you will find it again.
    A ship's last port of call determines which spheres it can move to. Port of call is the sighting or landing within a crystal sphere. If a ship heading for Krynn from Greyhawk accidentally ends up at the Realms, the Realms become its new port of call. It should be noted that ships in the Flow slow down when they encounter other bodies, such as ships and rogue planets, but this does not affect total travel time.

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©2002 Wizards of the Coast, Inc.

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Phlogiston, © 1989 Wizards of the Coast, Inc.
d20™ System, Conversion of Phlogiston ©2002, Michael Billard and Mark Doolan
Original Source: Concordance of Arcane Space

    Notes on this Conversion: In 2nd Edition spells that had extradimensional access had to have access to either the ethereal or astral plane. This is not the case in 3e where it seems that access to extradimensional space can be used from any plane. For those purist of the spelljamming setting may want to include the following for there 3e spelljammer campaign:
    Extradimensional Impedance: Spells and spell-like powers that open extradimensional spaces fail to work on the Plane of Phlogiston. This also includes magical items that create extradimensional spaces, such as portable holes and bags of holding.
    A special thanks goes to Michael Billard for giving me special permission to use portions of his write up of the phlogiston.