Introduction:
The purpose of this essay is to explain the nature of the barrier that wards the Prime Material Plane of Therra from rampant incursions by outsiders. In addition, related topics such as planar travel and summoning of outsiders are touched upon, as well as the issue of outsider knowledge and travel to remote parts of Therra. Finally, the recent events and their consequences for the Maug are explained.
Any player wanting to better understand the nature of outsider threats should read this document.
The Cosmic Barrier:
The Time of the Deceiver:
There is, indeed, a ward around Therra. This ward was created, amazingly enough, by the Deceiver himself. The Deceiver coveted the Prime Material Plane for himself, and he feared that the legions of good outsiders (and even perhaps an alliance of neutral ones) would be able to possibly overthrow him, or somehow awaken the Gods, or at the very least would successfully hinder his conquests. So fixated was the errant god on Therra, that the infinite planes of the multiverse meant little, if anything, to him, except as a supply of fiends to serve him and as a source of nuisance from the goodly beings there who opposed him. He was content to let the Astral Plane and its many demi-planes go their own way without little interference from him.
And so, with the rest of the gods in Slumber, the Deceiver gathered to himself as many fiends and minions that he could. These included the dreaded Maugs, righthand servants of the Deceiver, as well as a host of powerful tanar'ri, baatezu, yugoloths, and other foul minions. These came to Therra at his bidding, and before the forces of good could also make their way to the Material Plane, he erected the Cosmic Barrier.
Through this Barrier, initially, no outsider could pass. With the thousands of fiends who had come to his bidding before the Barrier was in place, the god felt that he had the decisive advantage over the forces of mortalkind. But as the mortal races learned and plumbed the depths of arcane and divine magical lore, they learned of various ways to pierce the Barrier, at least temporarily, and summon outsiders.
Those outsiders who had come to Therra before the barrier was set essentially severed much of their link with the netherplanes. Although still extraplanar outsiders, and still even able to be banished from the Material Plane with sufficiently strong magic, they could abide on Therra indefinitely. However, there was a price to be paid for attaching themselves to Therra. They could be slain on the Material Plane, and by so being, they could not reform their essences. An outsider who predated the barrier who was slain on Therra was good and dead. Were he, instead, banished from Therra, he would return to his plane of origin and his connection to the Material would be sundered, and no longer could he return to Therra without being summoned by magicks.
After the Deceiver:
When the Heroes of the Gem awakened the Gods from Slumber, they saw that the Cosmic Barrier, despite its source, was a good thing. With all of the gods going into Slumber, the mortals would be vulnerable to incursions by outsiders, many of whom now had a taste of the Material Plane and mortal souls and relished more. Therefore, the Gods decided to leave the Barrier in place. During their brief stay out of Slumber, the gods attempted to round up as many of the more powerful fiends and outsider minions of the Deceiver as they could. Most of these had been destroyed in the March on Mordasht anyways, but undoubtedly some few escaped and desired to remain on Therra and do so to this day.
The majority of outsiders either left Therra voluntarily or were driven out. In doing so, they surrendered their link to the Material and became, once again, fully tied to their extraplanar origins.
Bringing Them to Therra:
As it now stands, bringing outsiders to Therra works like it does in most D&D worlds. Outsiders cannot on their own come to Therra. They cannot use their Greater Teleport ability to do so anyways, since that spell does not allow extraplanar travel, but more importantly, even those outsiders with the ability to Plane Shift (by whatever means) cannot use it to enter the Material Plane.
Effects Not Involving the Material Plane:
All of the below cover outsiders travelling to Therra. These do not always apply when outsiders travel from one non-Material plane to another non-Material plane. There is no Comsic Barrier, for example, between the Astral Plane and the Ethereal Plane. Thus, a wizard casting a gate spell on the Ethereal Plane to summon a tanar'ri would not have an astral projection of the tanar'ri step through. The actual tanar'ri, body and soul, will emerge.
Below are the most common ways outsiders make their way to Therra:
1. Summoning Spells
2. Planar Binding/Ally Spells
3. Gate Spells
4. Astral Projection
5. Planar Gates
6. Summoning from Other Outsiders
Summoning Spells:
Summoning spells essentially create a soul projection of a summoned creature similar to the projection created by an astral projection spell. The original creature does not go comatose, as with an astral projection spell, but experiences simultaneously his own reality and the reality of his projection. Thus the summoned creature feels pain when hurt and can enjoy pleasurable sensations as well. When the summoned creature reaches 0 hit points, his projection is essentially disrupted and the soul recoils back to its owner. The portion of soul summoned is not significant enough to harm the original creature in any way while it is summoned, though destruction of the summoned projection is said to be an unpleasant experience.
When a summoned creature's summoning ends, all of its equipment at the time summoned, as well as its physical body, disappear, just as with an astral projection spell.
Planar Binding/Ally Spells:
These spells essentially cause the creature called to enter a state of astral projection, just like the spell. The being's original body is comatose on its home plane, and technically subject to abuse or slaying in the netherworld. However, the long casting time of the spells usually allows the creature time to teleport to safety as the spell begins to pull and tug at its soul. Like normal stral projection, if the Material body of the being is destroyed, the silver cord retracts back to the original body.
Gate Spells:
Outsiders trying to pass through a gate spell to the Material Plane must do so by way of the Astral Plane. The gate spell itself creates an astral rift, a sort of wormhole through the Astral Plane that connects the source plane (the Material Plane) to the destination plane.When an outsider that has passed through a gate spell dies, it returns to its comatose body just as mentioned in the astral projection spell.
While outsiders that pass through the gate must astrally project, due to the effects of the Cosmic Barrier, Material native beings may pass through the gate completely, and, in fact, cannot astrally project through without use of the astral projection spell. Thus, Therran natives who pass through a gate spell to another plane are there body and soul and can be slain.
Astral Projection Spells:
In many senses, this is the default means for outsiders to come to Therra, though usually it is by way of other spells or items that end up mimicing this effect. The reason for this is that while the Cosmic Barrier was desgined to keep out the outsiders physically, it was never made to keep them out spiritually. Why this is the case is not known, but some scholars think that since the soul of the deceased must pass through the Astral Plane to find their rest in the afterlife, the gods had to make the Barrier permeable to souls, and apparently this permeability works in both directions, whether by design or accident.
Astral projection spells work normally in Therra, as described in the spell. For the record, a being can only have a single astral projection at one time, and one cannot astrally project to the same plane as the original body.
Planar Gates:
Even planar gates cannot bypass the Cosmic Barrier. These function in the same way gate spells (see above) do. Outsiders passing through a planar gate transit via the Astral Plane and therefore must create an astral projection to do so.
Summoning from Other Outsiders:
This ability, common to many demons and devils, places the beings summoned into a state of astral projection no matter to which plane the being is being summoned. This means the summoned being is comatose on its home plane, and this is why such beings are loathe to be summoned without a suitable reward or reason.
Outsider Knowledge:
Outsiders can go many places. Many have the ability to use greater teleport to go whever they like at will. So, does it follow that outsiders have visited and know every continent in Therra?
The short answer is, yes, conditionally. As outsiders cannot come to Therra on their own, it stands to reason that they will mostly be familiar with those areas of the planet that have people who can and do summon them. Are there such beings present on continents other than Jerranq in Therra? Most certainly. Though possibly not in every region of every continent. Thus, outsiders as a whole are probably a good source of knowledge of some remote places in Therra and not a good source for others.
Take, for example, the moon Luna. Few if any summoners of outsiders are on the moon. Therefore, the only way an outsider could ever get to the moon is to be summoned somewhere on Therra and then somehow travel to the moon. And while it may seem that greater teleport would allow this to happen, see the next section.
Travel to Remote Parts of Therra:
Most of the continents of Therra are extremely isolated from one another. There has been little, if any, cross pollination of species between continents, and most scholars are almost entirely ignorant about distant lands and most commoners even doubt they exist!
How can this be in a world of magic, where spells like teleport and greater teleport exist?
In many D&D worlds, there are some geographical features that inhibit teleport. This is especially common in the Underdark, where both Greyhawk and Forgotten Realms include emanations that blunt teleportation spells underground.
The same concept is at work on Therra. Not only does Therra have faezress, the emanation of earth power that blunts teleportation underground, but for reasons not entirely understood by scholars, the oceans themselves also block teleportation. Teleportation across oceans and/or seas fails after about 100 miles per level. The same seems to be true of the upper atmosphere, such that it is impossible to teleport more than 100 miles per level into the atmosphere. The leading theorists on the subject think that teleportation is somehow utilizing the elemental power of both earth and air to punch its way through the dimensions, and that lack of either element inhibits teleporting. This theory, if correct, would accurately explain why teleportation is inhibited below ground (enough earth but not enough air), over or into water (no earth and/or no air), or high into space (no earth or air).
However, it does not explain why teleport spells can be used with impunity on many planes of existence that have no earth or no air. Clearly, while this theory may be correct, it must also be in conjunction with some factor that is uniquely Therran and is at work only on the Material Plane.
It is interesting to note that such teleport spells do not seem to pick a straight line (so to speak) when determining whether a too large body of water is passed. Instead, it seems that as long as a sufficient land connection exists in some form and length, the magic will function.
Whatever the exact machinations, the effects are obvious. Almost no one has travelled from Jerranq to one of the other continents of the planet. And no wizards take a picnic on the moon with the simple use of a teleport spell. Such regions are therefore remote, mysterious, and largely unaccessible even to mighty wizards.
Plane shift spells are another consideration. Why don't mages simply plane shift to another plane and then do it again from that other plane to a distant land?
The answer is that each continent is remote enough that each has its own specific planar fork. Knowing the planar fork for Jerranq will not allow one to plane shift to Sazhansiir (or vivce versa). When a mage learns the plane shift spell, he automatically gains knowledge of the tune necessary for the Material Plane, but more specifically, he learns the tune necessary for that portion of the Material Plane where he first learned the spell. Essentially, researching the spell between levels includes experimentation necessary to determine the tune of the region one is in.