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The Heavens Above and the Hells Below
A Treatise on the Cosmology of the World of Therra
by Devin Cutler


The purpose of this document is to set forth the general cosmology of the World of Therra. By cosmology is meant the structure of the world itself, its place in the material universe, and that place within the other planes. Included in this document will be an explanation of the seasons of Therra, the celestial bodies of the setting, and the various planes of existence. Therran cosmology does not closely mirror the traditional D&D cosmology, and borrows some of its precepts heavily from concepts presented in the world of Glorantha as designed by Greg Stafford. Therra is also a world of magic and mythological forces. As such, many of its characteristics are not governed by physics and real life logic, but rather by mystical forces that interact with the world.

This document is written from a rules point of view, meaning it is not written in-character. However, every effort has been made to distinguish what most Therrans know of cosmological matters. Nothing in this document is a campaign secret, and this document is open to perusal by all players in Therra.


  1. A Map of the Multiverse
  2. The World of Therra
  3. The Celestial Dome and its Inhabitants
  4. The Sun and the Moons
  5. The Inner Planes
  6. The Astral Plane
  7. The Outre Realm
  8. Life after Death

A Map of the Multiverse:

Refer to the following cosmological map of the Therran multiverse when reading the remaining text.

The World of Therra:

The World of Therra, or more properly the planet of Therra is a spherical body some 11,000 miles in diameter. Its circumference is therefore 34,500 miles, which is approximately on-third larger than the size of Earth. Therra is located at the center of the Prime Material Plane. It is the only planet in the plane. Therra does not move. It does not rotate on its axis, nor does it revolve around any other body. It is immutable and unchanging in its current position within the cosmos. At its point at the center of the Prime Material Plane and, even moreso, the multiverse, Therra is undoubtedly the most important location in the multiverse.

The planet of Therra was created by the gods. At its core was a great spherical gem, the Earth Seed, discovered from the very edges of the universe and even beyond by Neengrum. From this core Neengrum extracted the earth power and mixed elements from the planes of Fire and Earth to fashion a growing mantle around the Earth Seed. Soon other deities joined in, adding their own expertise to the growing planet. From the planes of Air and Water were the seas and atmosphere formed. And from varying mixtures of the six building blocks of creation (Fire, Earth, Air, Water, Positive Energy, and Negative Energy) was the planet Therra and the Prime Material Plane born, set amidst the currents of the Ethereal Plane.

Since Therra does not spin on its own axis, day and night are defined by the revolution of the sun and the two moons (Luna and Celteri) around the planet. In particular, the sun makes a revolution around the entirety of the planet once every day, moving from east to west. This motion of the sun is the result of a compromise that sprang from the Gods' War wherein Heleniarr and Ularinn agreed to share the world between them, half of it to be in daylight and half in nighttime at all times. The two moons, creations of Vinstarria, also revolve around the planet, though on their own sometimes erratic courses and time schedules.

The sun of Therra revolves over the equator of the planet, and there is not inclination or declination from this plane of orbit. Because of this, Therra does not experience its seasons for the same reasons Earth does. Instead, seasons in Therra are mystical patterns set in ancient times by the Gods as part of an accord to end the Gods' War. Thus, in Therra, winter is not caused by an axial tilt away from the sun, but rather because those are the months allotted to Lothar, God of the Cold, to be ascendant. Similarly, annual time is recorded in Therra not to mark a revolution of the planet around the sun, but rather the completion of a cycle of the four seasons.

On Therra, all parts of the planet experience the same season, though the planet is still warmer at the equator and more frigid as one approaches the poles. This is due to the sun's path along the equator of the planet. The sun is closer to the equator than it is to the poles of the planet, and its heat has to pass through less atmosphere when shining straight down on the equator as opposed to slicing diagonally through the atmosphere at the poles.

Additionally, while it is true that the farther north or south one travels in Therra, the lower the suns' zenith over the horizon at noon, the lack of axial tilt of the planet means that even the most northern and southern of climes receives the same hours of daylight in winter as in summer.

Therra does experience time differences between longitudes, as the sun travels westward across the face of the planet. When it is morning in Bleton, it is late afternoon in Antorium. And while, in Earth's ancient times this time difference was not an issue due to slow travel times, in a world of teleportational magicks that can transport a mage from one side of a continent to another, it is important to keep aware of the time differences.

Because Therra does not spin on its axis, there is no coriolis effect. Nevertheless, the planet does experience tidal influences, ocean wide currents, and even a jet stream. However, these phenomenon are largely mystically induced by the gods or agents thereof. The tides occur because Vinstarria has an ancient, mythological claim on portions of the oceans.

Therra has no plate tectonics. The planetary crust is stable on a continental basis, and there is no continental drift of any sort. Earthquakes are generally the result of subterranean upheavals caused by magma, temperature changes, or supernatural forces.

Gravity in Therra is the result of an affinity of all material things for their origin in the form of the Earth Seed. All material things have a mystic attachment to the seed of their origin, and this causes a sympathetic force to be exerted by material matter towards the center of Therra.

The Celestial Dome and its Inhabitants:

Above Therra revolves the Celestial Dome. The Dome was fashioned to shield Therra and the Prime Material Plane from the effects of both the Positive Material Plane, which of itself acts as a buffer between the Negative Material Plane and the Prime Material Plane. Stars are the result of jewels set into the Celestial Dome by Heleniarr to focus the light of the Positive Material Plane and allow its luminence to cheer the night. The Celestial Dome is approximately 13,000 miles above the planet, in a great sphere. This distance has been verified by extremely powerful mages who have managed to endure extremes of cold and lack of air to breathe and have flown to the top. These mages report strange beings living amidst the Celestial Dome and that at places there are holes and rents behind which no light shines.

The stars have been set into constellations by Heleniarr, at her whim, or in honour of the gods or some of their creations. From time to time a great hero blessed by the gods is also honoured by a new constellation. Such events are greatly honoured by Therran inhabitants.

The Celestial Dome revolves slowly around Therra in the same plane and same direction as the sun, though these make a single revolution once per year. Therefore, stars that are visible in the northern hemisphere are not visible in the southern hemisphere, and all stars are visible from the equator given the proper time of year. Stars visible vary longitudinally depending upon the time of year.

The major constellations of the Celestial Dome visible from Jerranq, and their seasons of prominence, are:

Canis, the Loyal Dog (Spring)
Amorany the Hero (Winter)
The Northstar (year-round)
Gimansh the Sailor (Summer)
The Serpent (year-round)
The Pearly Crescent (Winter)
The Dragon (Autumn)
The Blade (Summer)
The Elf's Bow (Spring)
The Northern Plow (Summer)
The Druid's Sicle (Autumn)
The Sheaf (Summer)
The Albatross (Winter)
Ursa the Bear (Autumn)
Lothar's Axe (Winter)
Neengrum's Bosom (year-round)
Flupnir's Rat (unpredictable)
Meredros' Cat (follows Flupnir's Rat)

Therra has an astrological tradition that is founded on the movement of Luna and Celteri past various constellations.

The Sun and the Moons:

The sun is the creation of Ularinn. It melds the essence of the Plane of Fire with the life giving attributes of the Positive Material Plane (which is why many undead cannot abide the sun), and it is believed to be a conduit to both in the form of a grand and perfect prism that resides in the heart of the sun and focuses the energies of both planes into a fiery sphere around it. The sun is believed to be approximately 36 miles in diameter and resides some 12,000 miles above the surface of Therra. Much of the spread and reach of the sun's rays comes from its bouncing light and heat off of the Celestial Dome and reflecting it back onto Therra. Many mystics of the Church of Ularinn hold the number 36 and its divisors (i.e. 4, 6, 9, 12, and 18) to be holy numbers.

Therra has two moons. The first, called Luna, is the most prominent. It zips around the sky in course that is even with the equator of Therra and the sun's path and the revolution of the Celestial Dome. The moon makes a complete revolution around Therra once every day. The phases of Luna have nothing whatsoever to do with the reflecting of light from the sun. Instead, Luna's phases are the result of a constant ebb and flow of influence between Vintarria and Ularinn. Vinstarria's moon constantly robs Ularinn's sun of light, absorbs it into itself until it glows bright and full, and then has that same energy dissipate, until Luna is dark once again. Then the process repeats itself. If Vinstarria had her way, Luna would shine full on all nights, but Ularinn did not appreciate her siphoning energy from his sun, and so it is a struggle for Luna to steal away light from the sun, and in this struggle Luna eventually becomes fatigued and releases her stores of light, only to rebuild them once again.

Luna is a sphere of strange light-stealing rock some 25 miles in diameter and 8,000 miles from the surface of Therra. As such, Luna occupies slightly more of the sky than does the sun, and this allows Luna to occasionally pass before the sun and cause a partial or total eclipse.

Celteri was created by Vinstarria to woo the elves away from worship of both Galasiria and Heleniarr. She imbued small Celteri with a green glow, to remind elves in their nightly reveries of the green of ancient forests. It is some 9,500 miles above the surface of Therra and is believed to be a 4 mile diameter spherical crystal of amazingly complex shades of green, almost mesmerizing when viewed up close. The moon appears as a mere speck in the sky, but it glows more instensely than any star. Celteri is a chaotic body, and it moves across the heavens in a pattern that is either random, has such a long cycle that even the elves cannot determine it (or perhaps it is still in its first cycle), or in such a complex pattern that even the most intelligent of astronomers cannot fathom it. No matter what the truth, the appearance of Celteri is always something of a surprise, and when it appears in rare spots in the sky or next to significant constellations or Luna, it is often regarded as a sign or omen.

The Inner Planes:

The Inner Planes of Therra are the four Elemental Planes (including the quasi-elemental planes that form the merging between them), the Positive and Negative Material Planes, the Plane of Shadow, the Prime Material Plane, and the Ethereal Plane. Each of these is described below in a format compatible with the Manual of the Planes.

The Prime Material Plane:

The Prime Material Plane of Therra has the following traits:

The Prime Material Plane of Therra is a great sphere, formed by the Celestial Dome, some 37,000 miles in diameter with a circumference of 116,200 miles. At the centre of the plane is the planet of Therra, and orbiting around the centre are the sun and two moons, Luna and Celteri. The atmosphere of the planet extends as breathable for some 10,000 feet before beginning to thin, and by 20,000 feet is thin enough to pose a danger to normal breathers. There is almost no air above 30,000 feet, and beyond 40,000 feet there is naught but vacuum for another 12,990 miles.

Gravity on the Prime Material Plane exters towards the centre of the plane. The entire border of the plane is called the Celestial Dome, and it is composed of an unknown substance that is reputedly harder than adamantium. Nonetheless, great gems are set within, catching the brilliance of the Positive Material Plane behind it and twinkling as stars. In addition, other rents and sunders in the Celestial Dome are rumoured to hide tunnels or portals to other planes.

The Prime Material Plane is coexistent with the Ethereal Plane, coterminus to the Astral Plane, and has limited, spell-based access to the Plane of Shadow. In addition, elemental vortices exist, which are weak spots in areas that have particular affinites with elemental types. Vortices to the Elemental Plane of Fire may be found in the heart of active volcanoes, vortices to the Elemental Plane of Water may be found in the deep ocean, vortices to the Elemental Plane of Air may be found high in the atmosphere, and vortices to the Elemental Plane of Earth may be found deep underground. Finally, permanent portals between the Prime Material Plane and other planes may be present, created by magic or other powers.

The Prime Material Plane has a mystic barrier set around it that prevents outsiders from easily entering it without the use of magic, specifically magic originating on the Prime Material Plane. This barrier was originally erected by the Deceiver to keep out many of the Celestials and other outsiders of Good, while allowing evil outsiders to come to Therra and remain. When the Deceiver was imprisoned in Slumber, the awakened Gods saw that this barrier could be used to protect mortals by hedging out all outsiders, and so this was done.

The Positive Material Plane:

The Positive Material Plane of Therra has the following traits:

In all respects the Positive Material Plane is athe same as the Positive Energy Plane as described in the Manual of the Planes, except there is no Hospice here.

The Negative Material Plane:

The Negative Material Plane of Therra has the following traits:

In all respects the Negative Material Plane is the same as the Negative Energy Plane as described in the Manual of the Planes, except there are no Death Heart or Castles Perilous here.

The Plane of Shadow:

The Plane of Shadow of Therra has the following traits:

The Plane of Shadow is a bizarre place formed by the merging of the Positive and Negative Material Planes. Where they merge, a region of shadow has been created. The Negative Material Plane is a destructive force, and seeks to overwhelm the Positive Material Plane and consume the life energy of existence. The Plane of Shadow represents that portion of the Positive Material Plane where the negative energies have bled over. As such, the boundaries of the Plane of Shadow merge with the Positive Material Plane on one edge and the Negative Material Plane on the other. This makes the Plane of Shadow finite in width, though as it forms the border between two infinite planes, it is, itself infinite in length. The width of the plane varies, and being infinite in length, no true census of its width can be given. Most observers, natives, and travelers to the plane tell that the width generally varies from 100 miles to 1,000 miles. At the boundaries, the plane gains mild energy traits commensurate with the nature of the border. Eventually, this trait increases until the respective Energy Plane is entered.

Unlike in the Manual of the Planes, in Therra the Plane of Shadow is not a shadowy mirror of the material world. Instead, it is a place of a roiling mixture of ether, positive, and negative energies so intermixed so as to form a uniformally grey mist. Visibility in the plane is half of normal, comparable to a misty twilight on the Material Plane. This means encounter distances are halved and opponents gain concealment unless under the effect of illumination.

Dark mirages do exist, for the substance of the plane is drawn to wherever light and dark mix, and they do so on Therra. As such, occasionally, as shadows bleed into the material world, sometimes echoes of the material world bleed back onto the Plane of Shadow. These form islands of solidity amid the grey murk, and often these islands form haunting echoes of material Therran locations. Over time, enough islands have formed (and not yet broken apart) so that it is not difficult to find a chunk of "land" floating through the plane.

Darklands, shadowquakes, and astral portals exist in the Plane of Shadows. The Shining Citadel does not.

Gravity in the Plane of Shadows is generally towards the nearest, largest chunk of "land". This is, in fact, how most travelers travel in the region, by simply allowing oneself to float towards the nearest island or chunk of "land". Larger pieces exert more gravity over greater distances. The actual force of gravity is much greater in the Plane of Shadow, but overall less is exerted at any one spot due to the lack of large land masses. As such, a chunk 1 mile in diameter and 500 ft thick (roughly 10 billion cubic feet) will exert the same amount of gravity as normal for Therra. This gravity quickly degrades, however, as one moves away from the chunk, such that a mere 50 feet up gravity is half, and it halves again every 100 feet thereafter. For every additional 10 billion cubic feet, add 50 ft to the distance of the first light gravity band and 100ft to the distance of every additional gravity band. For smaller chunks, the gravity band distance will shrink proportionately to the amount of volume of the chunk. So, for example, a chunk with 1/3rd of the volume would have 1/3rd of the gravity band distances. While it may be noted that this progression is not linear (those volumes above 10 billion cubic feet progress at a different rate than volumes less than 10 billion cubic feet), the DM can simply wave this off as an unknowable quirk in the structure of the plane.

Those familiar with geometry will note that the formula for computing the volume of a solid is length x width x height. This means a 1 mile diameter chunk 500 ft thick would have a volume of pi x radius squared times height. That would put it at roughly 10.2 billion cubic feet.


A chunk of 100 billion cubic feet will exert normal gravity for 500 feet, then half gravity for another 1000 feet, then quarter gravity between 1501-2500 feet, and so on.

A chunk of 2.5 billion cubic feet will exert normal gravity for 12.5 feet, then half gravity for 25 feet, then quarter gravity for 38-62 feet, and so on.

The effect of half gravity is equivalent to the Light Gravity trait. The effect of each halving of gravity thereafter doubles the effects of Light Gravity. After 1/8th gravity, the effects are treated as No Gravity for most purposes, although an object or being will still slowly drift towards the body exerting the most gravity upon it.

No body on the plane, however large, exerts more than the equivalent of normal Therran gravity.

The Elemental Plane of Air:

The Elemental Plane of Air of Therra has the following traits:

In all respects the Elemental Plane of Air is as described in the Manual of the Planes.

The Elemental Plane of Earth:

The Elemental Plane of Earth of Therra has the following traits:

In all respects the Elemental Plane of Earth is as described in the Manual of the Planes, except that in Therra, creatures of the earth subtype can always breathe on the Elemental Plane of Earth even if there is no oxygen. These creatures are sustained by the earth power of the plane, which obviates their need to breathe air while on the plane.

The Elemental Plane of Fire:

The Elemental Plane of Fire of Therra has the following traits:

In all respects the Elemental Plane of Fire is as described in the Manual of the Planes.

The Elemental Plane of Water:

The Elemental Plane of Water of Therra has the following traits:

In all respects the Elemental Plane of Water is as described in the Manual of the Planes.

The Ethereal Plane:

The Ethereal Plane of Therra has the following traits:

In all respects, the Ethereal Plane is as described in the Manual of the Planes. The Therran Ethereal Plane includes the Deep Ethereal, which connects the various coexistent nodes of the Ethereal Plane. Ethereal curtains exist, but they exist only to the Therran planes, not to any of the "Outer Planes" of the standard D&D cosmology. The Ethereal Plane is neither coterminous nor coexistent with the Astral Plane, and it is not possible to turn ethereal while on the Astral Plane or any of its demi-planes. However, the Astral Plane connects at every point with the Ethereal Plane (but not vice versa). This means that an Ethereal creature could cast an astral projection spell and travel to the Astral Plane. But an Astral creature could not cast an ethereal jaunt spell.

The Astral Plane:

The Astral Plane is presented in a format compatible with the Manual of the Planes:

In all respects, the Astral Plane is as described in the Manual of the Planes, except there are no dead deities littering the plane. Astral colour pools exist, but they exist only to the Therran planes, not to any of the "Outer Planes" of the standard D&D cosmology.

The Astral Plane serves a much more important place in the Therran cosmology than it does in the standard D&D cosmology. Whereas in the standard D&D cosmology the Astral Plane is primarily a conduit to the Outer Planes, in Therra, the Astral Plane IS the Outer Planes. Most Therrans refer to the Astral Plane as the Netherplane or Netherworld. The Astral Plane is home to a great many outsiders, servants of the Gods at the creation of the universe. The Astral Plane is where the Gods were born, some say congealed out of the pure thought of the plane. Whatever the origins of the plane, the Gods first fashioned their homes upon the plane, then peopled it with their minions and servants before embarking on the creation of Therra.

When the Gods went into Slumber, they bequeathed their respective realms in the Astral Plane to their most powerful minions. The Deceiver did likewise when he barricaded himself onto the Material Plane, and as such the Astral Plane became a battleground for various factions of outsiders, each seeking to dominate the plane that was, for most intents and purposes, abandoned by the Gods.

Because the Astral Plane is composed of the essence of spirit and soul and thought, powerful entities can morph the plane, creating pockets or islands that are fashioned to their liking. In some cases, very powerful beings can even pinch off a part of the plane, closing it in on itself to form a demi-plane. In many ways these demi-planes function similarly to the standard D&D Outer Planes, in that they are usually ruled by a powerful outsider of a given alignment, they are populated by its minions, and the demi-plane reflects the preferences of its owner, both in appearance and in its traits.

However, there is no rigid hierarchy of alignment-based planes. A given demi-plane might have been at first created by Ringkol, the God of Dance. When he left, he may have bequeathed the demi-plane to a powerful solar. The solar may have been overthrown by a pit fiend, who spent millenia altering the plane into a fiery, hellish furnace. He may have finally been slain by githyanki who now are building a fortress on the plane. Some demi-planes are destroyed or erode away without a powerful mind to keep it stable. Demi-planes can be finite or infinite, depending upon the powers of their current master or original creator. When entering a demi-plane, astral travelers form a solid body just as if entering one of the Outer Planes in the standard D&D cosmology.

Entering these demi-planes can be difficult. Each demi-plane can have a colour pool associated with it, but given the infinite numbers of such planes, it is often difficult to judge between such subtle shadings of colour and pattern. Therefore, some colour pools are purposefully marked by the masters of the plane with a pattern or symbol to identify it.

Outsiders native to the Astral Plane cannot enter the Material Plane, except by way of spells or by portals. In any event, the barrier erected by the Gods prevents them from entering in their native bodies. Instead, they must route through the Astral Plane and then form new bodies on the Material Plane. This means that outsiders that appear on Therra, for example by means of a Planar Ally spell, who are slain simply return to their bodies on their home plane. This also means that their home bodies are inert and unaware while their spirits travel the Astral Plane or are embodied on the Material Plane. Killing an outsider on the Material Plane banishes it to the Astral Plane for a variable period of time depending upon the power of the entity and its inherent nature. A good rule of thumb is 1D100 years divided by the creature's HD.

Here is an example of a demi-plane taken from the scenario "Enough is Enough!":

Zirriloyut's domain is actually a portion of the demesne of Demogorgon, who is now imprisoned in Slumber. Demogorgon's domain was claimed by many of his more powerful servants, and several great wars were and are being fought in order to control the domain, which is a demiplane floating in the astral plane.

The domain has the following traits:

This plane appears to be a vast plain of cracked, baked mud, with a fiery red sky full of roiling clouds. Despite the fiery appearance, the plane is actually somewhat chilly.

Few mountains or other features mar the inhospitable landscape, but those few are amazingly pronounced, rising in needle-like spires hundreds or thousands of feet into the air. A few of these are volcanoes that spew ash or poisonous gas into the air.

The portal enters the plane in a large gully, some 15 feet deep and 20 feet wide, that runs relatively straight in both directions. The portal appears as a small cave (approximately 20 foot square) that has a deep purple glow in its rear.

DMs can use the encounter charts for Abyssal and Hellish encounters in the Manual of the Planes. Assume an encounter 8% per hour and a 50% chance of using either table.

The Outre Realm:

Vague rumours, hints from mad philosophers, and guesses by logicians and mystics suggest that there is a strange and remote realm beyond the membrane that houses the multiverse of Therra, and that amazingly different or exceedingly dangerous beings inhabit this Outre Realm. Little beyond guesses and speculations are known, though on occasion the appearance of a strange and heretofore unknown creature is sometimes attributed to the Outre Realm. It is also believed that the border of this realm and the multiverse is a place where the sea of Chaos laps upon the shores of reality is a realm called Limbo, where dwell the slaadi and the githzerai.

Life after Death:

When a being dies, its soul enters Slumber if it served one of the gods or venerated some or all of the gods. Being an astral body, the soul of the dead enters the Astral Plane and begins to fly towards the Hall of Slumber, the only point on the Material Plane that is coexistent with the Astral Plane. The soul, in death, is attracted like a moth to a flame to the sleeping essence of Mergurr, the God of Death. Here, the dreams of the God judge the soul and determine to which God or Goddess the soul shall cleave. Such a soul joins with its patron divinity or divinities in Slumber, and basks in the adjacent dreams of the the God or Goddess for an eternity.

In Therra, most outsiders are not formed from the souls of the dead, but have existed since the beginnings of Time or were created by the gods as servants. Nonetheless, the ranks of outsiders is somehow renewed, and it is believed that they, good and evil, sometimes cull the souls of the dead as they flit across the Aster towards Slumber. For good outsiders, this is usually a voluntary act, often reserved for the most virtuous of souls. For evil beings, this is often akin to slavery or kidnapping.

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