Mithis Plane¶
"Where the other Energy Planes form a bridge between Material, Astral and Elemental Planes. The Mithis Plane forms a barrier between the Abyss and the Material and Elemental." — Terrun Cosmology (S421)
Contested
This page is named in the open question Material Plane and the Mithis barrier. The 2026 Cosmology Revision says the barrier "began to significantly decay" after the Age of the Dark Sun; the 2022 Cosmology says it "completely disintegrated".
The Mithis Plane is the wall between the world and the Abyss. It began as an Astral Shard moved out of the heavens and bound to the Material as the Worldstone; it was mined by mortals as the source of arcane magic; it thinned, tore, was seized by an archdemon, and at last was cut loose from the world altogether to become the Rift. The substance it is made of has its own page, Mithis; the stone it was bound into is the Worldstone.
Also called: the Mithis Energy Plane, the Mithis Astral Shard, Denitrus (the gods' name), the Abscission (strictly the barrier it forms), the Hollow (in the Sancturi age, see below).
Formation¶
"The Mithis energy plane was formed when an Astral Shard was moved from the Astral Plane to the Material. It was brought to insulate the Material Plane from the Abyssal Planes" (S421, S395). The Mithis notes agree: "Scholars surmise that is was once an Astral Demesne, moved to the Material Plane to form the Abscission (the barrier between the Abyss and Material). When the gods moved/created it, it was called the Worldstone and was bound to all life on the Material Plane" (S419). The Revision calls it "an additional barrier plane (the Mithis Plane) ... created to keep powerful beings from being able to leave the Abyss" (S001), and the history of the earlier ages names the act the Demonic Abscission: Kalar "took one of the shards and with help from many other Einar (and their shards) forged the Anthu'Mithis (Worldstone, which created the Mithis Plane)" (S386). Because the shard "once acted as the Gate to the Abyss", its ruin made it "a primary transit point for Demons trying to escape the Abyss" (S001).
Who controlled the stone changed with the ages. "It was initially controlled exclusively by the High Elves of Anthu'Mithis during the period known as the Elven Ascension/Pax Lothim Anthu. After the fall of the High Elves of Anthu'Mithis, the Worldstone fell under the control of the Twilight Dragons during the Draconian Ascension/Pax Draconia. After a long reign and under unclear circumstances, the Worldstone was destroyed, throwing the entire planet into apocalyptic chaos" (S419). That event is the Shattering; the ages are on Age of Dragons.
The Abscission¶
The Abscission is the barrier the plane makes, and it is self-repairing. "The magic of the Abscission originally prevented Demonic corruption, by automatically banishing demonic spirits to the Abyss. The Shattering destroyed the Anthu'Mithius (as well as most of the continent that it was on at the time). In doing so, the magic of the Abscission was greatly weakened. The Anthu'Mithius bound the Mithis together into a uniform field around Terrun. This field vanished and the Mithis became a free agent, though still purposed at maintaining the Abscission." Mortals then "started using Mithis for their own ends and turning it away from the work of the Abscission." Even so, "the Abscission is self-healing in that it naturally moves to redistribute its strength" (S519, S513; the same passage in the Compendium, S372, S384). After the Shattering "the barrier between the Material plane and the Abyss remained mostly intact, though weak enough that small holes could now be punched in it (Demonic Summoning)" (S386). The archive cosmology lists the plane's connections as "the other Energy Planes, Elemental Planes, Material Plane, and Abyss" and says, as of the energy planes generally, that "no known forms can visit" (S421).
Accursed places, Demonblight and Demonic Rifts¶
"The abscission can be locally weakened through repeated spellcasting or the repeated release of ethereal energy (death) in an area. Areas with a weakened Abyssal barrier that are known for demonic possession are often referred to as Accursed. In some cases the Abscission becomes so weak that the boundaries between Abyss and Material Plane have blurred, creating a region known as Demonblight. The demonic energy radiating from the Abyss into these areas kills or corrupts everything in the land around it. Animals that wander into these areas are immediately possessed by hordes of demons waiting for a chance to escape the Abyss" (S519, S513).
"A rift is a complete break in the Abscission wall. This allows demons in spirit-form to invade the Material Plane and scour the area looking for hosts. More powerful spirits require a larger rift in order to pass through. A Demonic Rift is not a natural or accidental event and requires extremely powerful magic for creation and maintenance" (S519). The Compendium adds that such rifts "are not stable and only allow some number of Demons through before closing. Stable Abyssal rifts are a nightmare scenario studied and feared by scholars", watched for by the Knights of Lothos and the Light of Kalar (S372). The first recorded rift was opened by the orc summoner Thu'karam in the First Rift War; another formed spontaneously beside a wizard college in the Second (S386). Where the barrier is strong, "Demonic magic is suppressed ... and is amplified in places where it is weak" (S372).
Spawning Rifts¶
The newest demon rules describe the thin places as they are now. "These rifts are places where the Abscission between the Abyss and Material planes is very thin. These rifts are very difficult to close and most scholars believe that closing one simply forces another to open somewhere else. These rifts usually spawn minor demonic spirits which often suffer complete essence decay before they can secure a host. More powerful spirits do occasionally cross over in these, but usually at a high essence cost relative to the power of the demon (which is why really powerful demons rarely cross this way and prefer to be summoned by their minions or mortal spellcasters)" (S333). Around such a rift "only small animals are available ... and even those are hotly contested" by the newly arrived (S329). A demon's Bond is the measure of "its link to the material planes — the tether keeping the demonic essence from being drawn back into the Abyss" (S334).
Decay and the Hollowing¶
"Over time, the Mithis barrier was repurposed by mortals as a magical power source and slowly weakened. It began to significantly decay shortly after the Age of the Dark Sun" (S001). Its "repurposing" is the whole history of Arcane Magic: "Mithis Magic is drawn from the Mithis particle which permeates the Material Plane and forms the Mithis Energy Plane. Mithis is a destroyed Astral Shard whose particles are claimed by proximity" (S208, S304). "Any sense of Astral ownership is now impossible. Mages have learned to tap into this free energy source" (S421).
Then the ownerless shard was claimed. In the Sancturi age "Mithis became a corrupted substance controlled primarily by the Archdemon Asmodeus" (S208), who "has taken complete control of the Mithis Plane and warped it creating The Hollow, and intermediate, fragmented plane between The Abyss and The Material" (S132). What let him do it was a piece of the Mithis Heartstone: "This is what has allowed him to take over defacto control of the Mithis Plane and bend it to his will", though "his hold on the Mithis plane is not as absolute as he would have everyone believe" (S132). The god Arcantus, displaced from his shard, dared not return to it, since "he would lose to a challenge by Asmodeus and Asmodeus would gain more control over the Mithis Plane" (S190). The Hollows that resulted, "demi-planes between the Material Plane and the Mithis Plane" (S146, S325), have their own page; the age's name for the corrupted substance, Malum or Irathus, is on Mithis.
Denitrus¶
The gods call the plane Denitrus. At the Council of the Quad, Aion, ascendant of Kalar, summoned the others "to discuss what action we can take in regards to the second abscission of the Denitrus plane, which the mortals are referring to as the Hollowing." Asked whether an archdemon had taken dominion of Denitrus, he answered: "Partly, yes. The archdemon is Asmodeus, one of the lesser of the nine ... it is only partial dominion, Kalar remains principal. However there is no one presently capable of casting Asmodeus out while Kalar still sleeps." Khemeia's reply set the pantheon against itself: "we must find a way to take dominion of Denitrus ourselves from Kalar so that we can cast Asmodeus out" (S031, S071). The council and its speakers are on the Astral Plane page and under Inwe.
Each shard its own plane¶
A campaign note on the Heartstone records the rules of the shard as a place. "Shard rules are that the only viable magic in the shard is that granted by the shard itself. Each shard is its own plane of existence. Shards do sometimes overlap, but not the Mithis shard. To gain control of a shard, you must defeat/banish its current owner ... or you may slowly capture it by occupying the shard (if it is abandoned)" (S182). Ownership of Mithis is claimed with the Astral Key at "the Apotheosis of Arcantus", whose access Asmodeus controls (S142). Both are Artifacts' matter.
Destruction and the Rift¶
The Cosmology of 2022 ends the plane: "during the Age of the Dark Sun, the Mithis Plane was destroyed and in its place, the Astral Folds formed (The Rift)" (S013). The Revision softens this to decay, but describes the same aftermath: "The decay has caused the shard-space to merge with the Shadow Realm and punctured holes directly through to the Material", and "the rift contains many old fragments of the Prime Material and Astral Planes: detritus and fallout remaining from the disintegration of the Mithis Plane. Things and places strongly tied to Mithis were more likely than not to end up in the rift after the end of the Hollowing Period (this was the 500 year time period during which the transitions took place)" (S001). The Fifth Age magic notes say flatly "The Mithis Plane is gone, its echo being the Rift and its bridges to Astral Shards (Astral Folds)" (S014). "Before the Mithis Plane was destroyed, demons commonly projected their spirits out of the abyss when summoned ... Now they are able to be summoned with their fully manifested demonic forms" (S018).
The last act was the Redemption. "An act of the Divine that destroyed all Hollows and removed Mithis from the world. The Mithis Plane has been fully extracted from the material, making it its own physical place known in common parlance simply as the Rift (an often unstable and shifting place). Scholars call this the Mithis Fracture. Divine Priests call it Perdition." Mithis metals "can still exist, but must be transplanted from (and energized on) the Mithis Plane. The Mithis Plane is still a bridge between Material and Abyss (but much more distant). Asmodeus still has a lot of control here" (S112). See The Redemption.
Earlier accounts¶
The archive cosmology sets the Mithis Energy Plane beside the Positive and Negative Energy Planes, a plane "used heavily as a power source for magic users" that no form can visit (S421, S389). The oldest magic rules make it the medium of conjuration: Conjuration "manipulates the mithis plane to create planar tunnels from any plane adjacent to the Mithis plane to the Inner Planes", Abjuration "can manipulate the mithis plane to protect from any extra-planar forces", and Summoning is "opening various kinds of gateways through the mithis plane" (S371). The newest magic notes do not name the plane but keep its one rule: Mithis energy "is only available to casters when on the Material Plane" (S205).
Gap
No source describes the Mithis Plane as a place one could stand in before its ruin, names the "second abscission" of Denitrus in any mortal record other than the Hollowing, or says how the plane relates to the Mithis Astral Shard that the Heartstone grants access to. Whether Denitrus and the Mithis Plane are the same thing is an inference the sources leave to the reader.