World Tree cosmology

Prior to the Spellplague the most commonly accepted structure of the multiverse was the World Tree Cosmology. In this model of the cosmos the planes, except for the anomalous planes, existed in a neatly arranged network often described as a vast tree in shape and form. In many ways, it retains several qualities of the earlier Great Wheel cosmology model and later World Axis cosmology model. Astral dominions, for example, are typically considered to exist "above" the elemental and energy planes (which later would blend into the Elemental Chaos), which likewise lies "below" the Astral Sea. Also, the Plane of Shadow, the predecessor of the Shadowfell, served as both a dark echo and a link between the Prime Material Plane and other worlds.

However, there are several differences, which are described below.

Astral Dominions
In the earlier World Tree structure of the planes elemental realms, the counterparts to the astral dominions, did not exist and the primordials had long been forgotten. As a result, the duality of the planes was generally interpreted along lines of good and evil, with those that adhered to neither side, laying somewhere in between. The dominions were hence divided into celestial planes and fiendish planes, each composed of a corresponding essence. These distinctions likely still exist in the new cosmology, but they are less recognized and considered less significant than the new distinction between astral dominions and elemental realms.

Celestial Planes
Celestial planes are planes composed entirely of good. All known celestial planes are also astral dominions, though this is likely not a necessity anymore than in the case of fiendish planes. In the World Tree structure, celestial planes were aligned "above" the elemental and energy planes and to the "left" of the fiendish planes. Generally, celestial planes are ruled over by goodly beings, though there are exceptions to the rule.

The known celestial planes from the time before the Spellplague were as follow, though the term could also apply to modern planes as well.


 * Arvandor
 * Just as in the World Axis, Arvandor served as the home plane of the Seldarine, though it also was home to the drow goddess Eilistraee before her death. Arvandor lay below Green Fields and above in the World Tree's branches and maintained portals to both Brightwater and Dragon Eyrie.


 * Brightwater
 * Brightwater was the home plane of Lliira, Sharess, Sune, Tymora and Waukeen. Brightwater lay above Golden Hills and below Gates of the Moon, which it later became a demiplane of, and portals were also maintained with Arvandor, Heliopolis, and Green Fields.


 * Dwarfhome
 * As in the World Axis, Dwarfhome was the home of the Morndinsamman, except for the duergar and derro deities. Dwarfhome at the time lay below Arvandor, at the very "bottom" of the celestial planes and was also contained within the structure of Mount Celestia, which at the time was a massive network of planes rather than a singular dominion.


 * Dweomerheart
 * The home plane of Azuth and Mystra, as well as their subordinates Savras and Velsharoon. The plane lay to the left of the House of the Triad and below the House of Knowlege before it was completely obliterated with the Spellplague and the death of Mystra.


 * Gates of the Moon
 * As in the later cosmology, Gates of Moon was inhabited by the goddess Selûne along with Finder Wyvernspur and Shaundakul. Gates of the Moon lay at the "top" of the celestial planes, bordered below by Brightwater.


 * Golden Hills
 * Home of the gnomish pantheon prior to the Spellplague, except for Urdlen, who tunneled beneath Hammergrim, the Golden Hills later became a demiplane within Arvandor. The Golden Hills lay below Brightwater and above House of Knowledge, with which it had a strong connection.


 * Green Fields
 * As in later years, Green Fields was the home of the halfling pantheon. Green Fields lay above Arvandor and below both the House of the Triad and Dweomerheart and also had a strong connection to the realm of the goddess Tymora within Brightwater. Green Fields was also, at the time, a part of the larger Mount Celestia.


 * House of Knowledge
 * Although Oghma himself is a true neutral god his home plane is a celestial plane and prior to the Spellplague bordered Dweomerheart and House of Triad below and the Golden Hills above, with which it maintained a portal.


 * House of the Triad
 * Part of Mount Celestia, House of the Triad was the home of the old Triad, as well as the gods Helm and Siamorphe. The plane, which had lain to the right of Dweomerheart, above Green Fields, and below House of Knowledge, represented the core of Celestia and was all that remained of the vast mountain after the Spellplague.

Fiendish Planes
Just as the celestial planes are composed entirely of good essence and are typically ruled over by good outsiders the fiendish planes are composed of the evil fiendish essences and are ruled over by such creatures as devils, demons, or even evil gods, among others. The fiendish planes in the "upper" branches of the World Tree, to the "right" of the celestial planes and above the elemental and energy planes. Through each of the fiendish planes flowed the River Styx, now a part of the Nine Hells exclusively. Though the distinction between celestial and fiendish planes has fallen out of favor since the Spellplague, it likely still applies, both to astral dominions as well as to the Abyss, an elemental realm.

The fiendish planes known prior to the Spellplague are listed below.


 * The Abyss
 * As after the Spellplague the Abyss was the home of demons and theorized to have 666 layers. However, prior to the Spellplague the Abyss lay in the Astral Plane, above the Nine Hells and the Blood Rift, putting it at the "top" of the fiendish planes.


 * The Barrens of Doom and Despair
 * The earlier name for Banehold, the Barrens of Doom and Despair were before the Spellplague, as after, the home plane of Bane, Beshaba, Hoar, Loviatar, and Talona. The Barrens lay below the Nine Hells and above Clangor.


 * The Blood Rift
 * The Blood Rift, recently merged with the Abyss, was home of the yugoloths, renegade demons who eventually reunited with their brethren in the Abyss sometime in the Hundred Years of Chaos. The Blood Rift lay slightly below and to the left of the Abyss, while sitting above the Nine Hells.


 * Clangor
 * The home of the goblinoid and kobold deities, Clangor was eventually dissolved by Bane after his conquest of the goblinoid pantheon. Before this it lay below the Barrens of Doom and Despair and above both Fury's Heart and the Supreme Throne.


 * The Deep Caverns
 * Later known as the Dismal Caverns, the Deep Caverns were home to those beings worshiped by denizens of the Underdark that did not reside within the Demonweb Pits, including some members of the Dark Seldarine. The Deep Caverns lay above the Fated Depths and below both the Demonweb Pits and Nishrek.


 * The Demonweb Pits
 * Home of Lolth and most of the drow pantheon. Shortly before the Spellplague the Demonweb Pits were actually located deep within the Abyss but during the War of the Spider Queen Lolth reforged it as its own, independent plane, below Hammergrim, to the left of Nishrek, and above the Deep Caverns. Unlike in most fiendish planes, the River Styx did not flow through the Demonweb Pits, which were separated from the other fiendish planes except for the Abyss, with which it maintained several portals.


 * The Fated Depths
 * The home of Sekolah and Blibdoolpoolp, the Fated Depths were located below the Deep Caverns, at the very "bottom" of the fiendish planes, through which the River Styx emptied.


 * Fury's Heart
 * Fury's Heart was the home of the destructive deities Auril, Malar, Talos, and Umberlee, located below Clangor and the Supreme Throne but above Hammergrim. After the Spellplague it merged with the House of Nature to form the Deep Wilds, except for Talos' portion, which the aspect of Gruumsh took with him to Nishrek.


 * Hammergrim
 * Home of the duergar deities Deep Duerra and Laduguer, Hammergrim was eventually wiped out by the Morndinsamman in a war shortly before the Spellplague. Prior to this, Hammergrim lay below Fury's Heart and above both Nishrek and the Demonweb Pits.


 * The Nine Hells
 * The Nine Hells, as in the years after the Spellplague, were the home of the devils, ruled over by Asmodeus, who at the time was an archdevil rather than a true god. At the time the Nine Hells resided below the flaming ruins of the Abyss as well as the Blood Rift, while above the Barrens of Doom and Despair, with which it maintained several portals.


 * Nishrek
 * As it is currently, Nishrek was the home plane of the orc pantheon, ruled over by Gruumsh. Before the Spellplague it lay below Hammergrim, above the Deep Caverns, and to the "right" of the Demonweb Pits.


 * The Supreme Throne
 * The home plane of Cyric, though prior to his ascension during the Time of Troubles the plane still existed, presumably under a different name, where it was ruled over by slaadi. Although the Supreme Throne was later sealed off as punishment for Cyric's murder of Mystra, the Supreme Throne at this time was open to visitors, though it, like the Demonweb Pits, lay outside the path of the River Styx, below Clangor and above Fury's Heart.

Unaligned Planes
Not all of the planes located in the upper branches of the World Tree were composed of celestial or fiendish essences. Nor were these planes wholly aligned either with the forces of good or evil, often serving as the homes of creatures on both sides of the battle between good and evil. Located between the fiendish planes and the celestial planes the unaligned or neutral planes held no allegiances to neither of the former two nor even to each other. Most of the unaligned planes that survived the Spellplague remained in the Astral Sea while others fell into the Elemental Chaos, such as Jotunheim.

The known unaligned planes located in the World Tree's upper branches were as follow.


 * Dragon Eyrie
 * The home of the draconic pantheon prior to the Spellplague, the Dragon Eyrie collapsed during the Spellplague, with Tiamat migrating to Banehold and Bahamut to Celestia, with the fates of the other gods left unknown. Dragon Eyrie was located at the "top" of the neutral planes, above Heliopolis, and maintained portals to Arvandor, Heliopolis, and the Nine Hells.


 * Heliopolis
 * Heliopolis was the home of the Mulhorandi pantheon, who vanished without a trace after the Spellplague, possibly into Abeir's cosmological twin to the local cosmology. Tiamat also resided here, as well as in the Nine Hells and the Dragon Eyrie. Heliopolis lay below Dragon Eyrie and above the House of Nature.


 * The House of Nature
 * Ruled both by Chauntea and Silvanus, the House of Nature was also home to Eldath, Gwaeron Windstrom, Lathander, Lurue, Mielikki, Nobanion, Shiallia, and the primordial Ubtao as well as various animal lords and the deities of many nature-oriented creatures such as centaurs. The Spellplague caused the House of Nature to split apart, with parts becoming the Deep Wilds while Chauntea merged her portion with Green Fields. The House of Nature lay below Heliopolis and above Warrior's Rest, whilst maintaining a portal to Arvandor.


 * Jotunheim
 * Located below Warrior's Rest, at the very "bottom" of the unaligned planes, Jotunheim was home to powerful titans worshiped by giants as gods. During the Spellplague, Jotunheim collapsed into the Elemental Chaos and was torn apart, though parts survived as elemental realms.


 * Warrior's Rest
 * The home plane of Garagos, Uthgar, and Valkur, Warrior's Rest resided above Jotunheim and below the House of Nature. Tempus, the ruler of Warrior's Rest after the Spellplague, also maintained a demiplane within Warrior's Rest known as Limbo, which later fell into the Elemental Chaos.

Cynosure and the Fugue Plane
Unlike the rest of the astral dominions, Cynosure and the Fugue Plane were not arranged within the branches of the World Tree but instead lay on opposite sides of it, like stones flanking its trunk. The Fugue Plane lay to the "left" whilst the Cynosure lay to the "right." This kept them isolated from all the other gods, thereby preserving their presumed neutrality and maintenance of the "Balance," as defined by Ao. In no major ways did they differ from their nature in the post-Spellplague years.

Planes of Power
Because the Elemental Chaos did not yet exist the elemental and energy planes were as neatly organized as the astral dominions, though they lay at the bottom of the World Tree, acting as the roots that fed into the Prime Material Plane and the Transitive Planes. Known together as the planes of power, these realities were incarnations of the basic buildings blocks of the universe. Each of the planes was very inhospitable to all but native or the most adaptive creatures of the plane.

It is not known for sure but it is likely that the planes of power were the result of the primordials' banishment from the local cosmology by Ao during the sundering of Abeir-Toril. Before this cataclysmic event the planes of power were likely blended together into an earlier version of the Elemental Chaos much as they are currently muddled together. Differences at the time in which the World Tree cosmology was the dominant model are listed below.

Elemental Planes
The elemental planes, which lay directly below the energy planes, embodied the four of the five basic elements in nature, air, earth, fire, and water, with an elemental plane of storm being oddly absent. The planes were extremely inhospitable except for natives of the plane, such as elementals, genies, mephits, and others. Each Elemental Lord, at the time believed gods rather than primordials, also made their home in the elemental planes. Several quasi-elemental and demi-elemental planes also exist, sitting at the junctures between the elemental planes such as the Elemental Plane of Cold, which lay between the Planes of Air and Water.

The primary Elemental Planes are listed below.


 * Elemental Plane of Air
 * The primordial Akadi ruled the Elemental Plane of Air, home also to air elementals such as djinns, lay furthest to the "left" of the elemental planes, next to the Elemental Plane of Water. After the Spellplague the Elemental Plane of Air collapsed into the Elemental Chaos, except for fragments such as the elemental realm of Sky Home and a few djinn motes.


 * Elemental Plane of Earth
 * Ruled by Grumbar, the Elemental Plane of Earth lay furthest to the "right," adjacent to the Plane of Fire. Home to earth elementals such as the dao the Plane of Earth collapsed almost entirely into the Elemental Chaos during the Spellplague except for Root Hold, Grumbar's realm.


 * Elemental Plane of Fire
 * Kossuth, the mightiest of the Elemental Lords, ruled this fiery landscape that was paradoxically both the most lethal and the most prolific in native life of all the elemental planes, home to the highly successful efreeti. The Plane of Fire, which lay between the Planes of Earth and Water at the "bottom" of the World Tree, was mostly dissolved during the Spellplague like the other elemental planes although the City of Brass and the Undying Pyre both survived its destruction.


 * Elemental Plane of Water
 * Istishia ruled this water-filled realm, which lay between the Planes of Fire and Air, at the so-called "bottom" of the World Tree's "roots," and was home to water elementals such as mereids. After the Spellplague most of the plane was destroyed, although Istishia still rules over its successor plane, the elemental realm known as Cresting Spires.

The Energy Planes
Sitting just "above" the elemental planes were the energy planes, which were no less extreme than their elemental counterparts. During the Spellplague the two planes collapsed, for the most part, into the Elemental Chaos. The energy planes were home to very few lifeforms and neither any deities nor any primordials make their home in either of the two planes, which are described below.


 * Negative Energy Plane
 * A dangerous realm from which the negative energies that helped to fuel undeath flowed the Negative Energy Plane lay to the "left" of its neighbor, the Positive Energy Plane. During the Spellplague it fell mostly into the Elemental Chaos, but not before the goddess Shar folded part of it into the Plane of Shadow, forming the Shadowfell.


 * Positive Energy Plane
 * The opposite of its neighbor, which lay to the plane's left, the Positive Energy Plane was a realm filled with intense radiant energy. No less lethal than the Negative Energy Plane, the Positive Energy Plane eventually collapsed into the Elemental Chaos. Also known as the Plane of Life.

Parallel Planes
Prior to the Spellplague the nature of the parallel planes was unknown. The Feywild was all but forgotten and the Plane of Shadow, the world's dark echo, was considered a one of a kind oddity. However the parallel planes did exist in much the same manner as they have since the Spellplague, though in a more elusive and unknown manner.

Faerie
Prior to the Spellplague, the Feywild was almost entirely unknown. Well-read scholars did know, however, that the Tel'Quessir were not native to the Prime but rather outsiders who had arrived in the distant past. This realm was known to scholars of the time merely as "Faerie" or perhaps the "Plane of Faerie" and was thought of a twilight land lush with forests, home to the fey and their Seelie and Unseelie Courts.

Sildëyuir
Likewise, most scholars were not aware that the "demiplane" of Sildëyuir was merely an echo of the Yuirwood in Aglarond, considering it a separate plane of existence. It was best known at the time as the place of origin for the star elves.

Transitive Planes
The transitive planes differed little prior to the Spellplague to how they operate now, though the Elemental Chaos had yet to form and the Shadowfell was still divided into the Plane of Shadow and Negative Energy Plane. During the years prior to the Spellplague the term transitive plane was also used more commonly than it was afterwards.

The major differences of the transitive planes are outlined below.


 * Astral Plane
 * The former name of the Astral Sea, the Astral Plane's nature as a fundamental plane was unknown prior to the Spellplague. Likewise, just as the dominions were wrongly believed infinite the Astral Plane was wrongly believed infinitesimal, when it was in fact, infinite in size. The few bits of matter scattered throughout the vast plane were mostly portals leading to every plane in the cosmology.


 * Ethereal Plane
 * The Ethereal Plane was a misty continuum that coexisted with the Material Plane. Individuals within the Ethereal Plane could see into the Material Plane, but not vice versa. It was accessed by spells such as etherealness and ethereal jaunt, as well as various portals scattered through the planes. The Ethereal Plane was destroyed during the Spellplague, though its exact fate is unknown, perhaps being folded into the Astral Sea, Shadowfell, or both.


 * Plane of Shadow
 * The Plane of Shadow, prior to its transformation into the Shadowfell, acted as a transitive plane. The most common way of accessing the plane is through spells and abilities like shadow walk, most often used for covering great distances on the Material Plane undetected and unhindered. Mask and Shar both made their homes within the Shadow Plane and it was through Shar that the plane was later remade into the Shadowfell.