Elemental Planes
by RobinAs according to canon, it is almost unsaid, but the Elemental Planes are thus near to the Prime Plane (belonging to the Inner Planes) they are affected by the same Elemental Rules as the Prime Plane, but in a much lower degree of intensity.
From the Rules encyclopedia (but my additions are Bleu)
Each elemental plane is a universe much like the Prime Plane, but all the material is a dominant element. The elemental matter collects in clumps (planets, moons, etc.); it can exist in solid, liquid, or gaseous or energetic form. For instance, in the elemental plane of Water, the atmosphere is an unbreatheably thick fog, the seas are made of water, and all land, solid objects, and even solid creatures are made of ice—ice which may be so hard and imperishable that it resembles crystal and does not melt in warm temperatures.
The strange creatures of the elemental planes are mixtures of solid and liquid material, held together by a life force of thought and energy (much like creatures on the Prime Plane). When a planet exists on an elemental plane in roughly the same "position" as a planet on the Prime Plane, natural vortexes and wormholes appear, connecting the planets on each plane. Thus, for the "normal" D&D world, there are four other planes in similar positions, one on each of the elemental planes. Other planets in the Prime universe might not have corresponding elemental planets; another world might thus be missing one or more elements.
Components of the Elemental Planes Table
| Type or Component | Elemental Plane of Air | Elemental Plane of Earth | Elemental Plane of Fire | Elemental Plane of Water |
| Atmosphere | Air | Dust or Soil | Plasma, Electrical clouds | Fog, Airy Water |
| Liquids | Invisible Airy Liquid(or quicksilver like) | Mud, Oil or cool Lava | Liquified Fire or Lava | Normal Water |
| Solids | Solid Clouds | Earth or Stone | Solidified Fire | Crystaline Ice, Ice |
| Energetic | Hot waves or magic | Fiery Magma or Heat waves | fiery sun | Bright Boiling Water |
Energy Would be thus similar on all the Elemental Planes, but probably visually much larger on the Plane of Fire and smaller on the Plane of Water, On Air, and Earth it would be about equal
Electrical, and waves would be near to equal on all Planes, but may be more visible on the Earth and Fire Planes
The creatures would thus be composed more or less similar. Bones as Solids, Veins as liquids, Food channel as Air, but the energy (nerves, brain) would be mostly electrical with the brain as a mixture. You would be able to find elemental creatures adapted to the elemental shape of that plane...i.e. Earth Elemental fish= Lava fish, Air elemental Tree= like trees, Water Elemental rodent= living ON land, etc
There would thus be an Elemental Sun, moon, and the movements and effects would be similar to the Prime Plane
The most living mater would be Elemental Plantlife of which only a few would be somewhat recognizable similar to the Prime Plane,
Food =energy would be similar to the Prime Plane...a Sun-like object would direct energy to plant-like objects, which would be eaten by animal like objects, which would be eaten by Plant like objects, and you have the basics of an ecological system.
The void between Planets would be similar...being void. Some elemental planets might or might Not exist on relative positions to Prime Plane Planets. The more towards the Astral Boundary=the further away from the Prime, the more often this will happen.
Elemental in the Prime plane desire the same food as on their respective Planes. Earth Elementals would thus crave crystal like plants. Medusae(as being a predator) craves biomatter discharching the other elements by petrification), Water Elementals would thus feed on crops of elemental Algea. etc.
As thus if you reflect the prime Plane map to the other elements, the contours would be similar, but Water Elementals would be concentrated in the water, and the land being least interesing to them. Fire elementals would be mainly concentrated on the land like you proposed, Earth elementals would concentrated similar as Prime Planes mostly ON land(but often live more within than on (hence their phasing ability), air elementals would on the "land" too, but also high above it.
Personally I assume them being able to fly through many clouds in another direction than the gravity pull, but on it with the gravity Pull. They would however do so only on known routes or research, as thus the might even be able to view the Hollow World of their own, where it not the energy based Worldshield in between (which to them would be a wall of hot energy instead of fire.
The gravity pull on these Planes is similar to the Prime plane
All these Inner Planes have connection to the Dimensions of Limbo (upon Death), Fairy Realm, among others.
Nice other easily adaptable material;(especially to find elemental creatures)
Manual of the Planes (TSR 2022) (this being the most adaptable to Mystara!! with one major difference Plane of Earth is NOT a solid Plane, but shape like the prime, as described above. many Elementals however, are able to Phase into the ground and reside there. As thus caves, tunnels, will exist enabling most other creatures to traverse where they will.
BUT keep in mind the D&D version does NOT encompass the Quasi Elemental Planes, These do not exist, and are Ethereal Plane instead, or Elemental Plane. Similar to the Quasi-elemental, negative and positive planes. Neither of these do exist on Mystara.
Other interesting
AD&D2 OP1 Tales of the Outer Planes Multi Levels of Set games
AD&D2 Planescape - The Inner Planes,
The planes are aranged in a very simple way.
Imagine 5 large marbles (one multi colered/green (Prime), one Red(Fire), One blue(water), one White/yellow (air), one Brown(matter)and a ball just as wide as three marbles in line. Place the Prime Plane ball inside, and the Elemental ones around that one, fill the ball with grey slime (resembling Ether). As the ball is closed, and the elemental planes always keep the same distance from oneanother around the Prime Plane due to Gravity issues, there is movement possible around the Prime, but the relative positions are always fixed. This would thus explain temporarily Elemental Gates (open when near, closed when far). As the Ethereal plane is chaotic, this pattern is very difficult to discern.
If you would place other objects around it, underneath and above, you would be able to imagine thus the Outer Planes.
Maybe indead like in AD&D2 the most near would form a sort of ring attached to the Ball(the ball being the Astral Boundary). Imagine the most nearby Outer Planes (in whatever shape) as sort of competing to keep near as possible to the Ball(with inside the Prime Plane). Thus the Elemental Ring of AD&D2 would NOT be a ring but several nearby Outer Planes more or less evenly aranged outside the inner Planes ball. the further away, the more distance between the outer Planes.Example AD&D2 Hades, with its chaitic 666 layers would be a weird clump attached with only a single Plabe to the inner Plane ball. Twin Paradises(2 planes) would be a oreo like plane swirling on its edge attached to the Inner Ball. Between this mass you would seem hundreds of vortices, of which a few haf grown into planes themselves(Yggdrasil would thus resemble roots growing between the planes, Styxx would thus slither like a stream between the Lower ones, and a large glob of water would be between a few upper outer Planes(being Oceanus).
I would even go thus far that the Elemental Planes and their relative position dictates the location of several Outer Planes (chaotics more near to Energy and Lawfuls more near to Matter for example. As thus the elemental makeup of outer Planes would also be affected or even dictated in one way or another on the composition of said plane. as thus it is possible a type of element will be less available or extremely rare not at all (for example An outer Plane could have no liquid elemental shape Which is water based, as thus it would also have no time and being an planar prison. more often any plane holds the same elemental shapes and energetic forms as on the inner planes, but rarely in a balanced form as the inner planes. It could be an outer plane thus affects time/energy/matter/thought completely different than any other plane due its composition.