In the SRD, the Astral Plane is considered the essential bridge between worlds. In the Wilderlands canon, that distinction goes to the Shadowlands (and in my take on the setting, the Ethereal Plane is just the doorstep of the Shadowlands). This shouldn’t make a difference to anyone but a rules nerd.
The ether, sometimes thought of as a plane in its own right, is usually considered part of the Shadowlands. It is coexistent with the material plane and with the Shadow. It is a haunted, foggy place whose mists occasionally extend into the material plane when patches of real fog occur on sites rich with negative energy.
The ether is almost empty of objects and obstacles, but savage beasts and ghosts sneak up from the Shadow to hunt. More rarely, beings from other planes breach the mists.
The ether is coterminous with the astral plane and the Dream. Indeed, some scholars simply consider all of these places to be part of the Shadowlands. Some Dreaming folk, particularly hags, are fond of traveling the ether to spy on the “other side” of their mortal prey. Raiding parties, especially goblin, may gather in the ether to scout a material location. Astral beings rarely travel this far, but those that make the journey are typically information gatherers with specialized skills and/ or equipment.
Travel in the ether
In the ethereal mists, there is an extra axis of movement. Moving “down and to the left” (sinister) takes travelers toward the Shadow. This is the natural trajectory of the dead, who arrive one round after death. For other ethereal travelers it takes 1d6 rounds of flight at any given moment to enter the Shadow from the ether. To make the transit together, travelers must maintain physical contact. Even a moment of separation while flying sinister will result in travelers arriving separately.
The ether is “up and to the right” (dexter) from anywhere in the Shadow, and is reachable in 1d6+1 rounds of flight in the correct direction. This is also the direction needed to reach most divine realms. Like traveling from the ether to the Shadow, continuous physical contact is required to make the journey together. Unlike in the ether, however, the Shadow has normal gravity, and some say that magic is fickle in the lands of the dead.
When the ether breaks through mundane fog, mortals face special peril. The sounds become a little more muted as the fog thickens, and the ground seems a bit springier. The traveler might be lucky enough to continue through this overlap normally, but the slightest mis-step or stumble will send him careening into the ether. While this planar breach is in effect, ghosts and other denizens of the ether can physically interact with the material plane, because they are effectively all on the same plane.
Mortals who can fly may navigate such planar breaches, entering or leaving the ether as they see fit. Flying animals have an instinctive sense of the ethereal directions, and veer dexter whenever possible.
Ethereal creatures can wander out of these fogs, but the breach is almost as dangerous to denizens of the Shadowlands as it is to mortals. Shadowlands creatures (including the deceased) cannot heal while in the material world, and suffer 1 HP of automatic damage per day in the harsh glare of the material plane. After dying in the material plane, the creature will reform in the Shadowlands per usual.
The ether has the following planar traits:
- No gravity. Those who cannot fly continue on their original trajectory until something intercepts them.
- Normal magic. Note that effects with the [force] descriptor work sinister (from the material to the ether, or from the ether deeper into the Shadowlands). The Transdimensional Spell feat allows spells to target creatures that are dexter to the caster, if they can be seen.
In all other respects, the ether is a part of the Shadowlands, and functions accordingly.
Ether vs. material
The ether is coexistent with the material plane, separated by a planar membrane that is virtually indistinguishable from the ambient fog. Through the membrane one can make out hazy shapes with muted colors and fuzzy borders. Only the loudest of sounds make it through the mists into the ether.
While the material plane is visible and faintly audible from the ether, the reverse is not true. Without special powers or spells (like true seeing), ethereal creatures are invisible, incorporeal, and inaudible from the material plane. Some creatures who haunt the ether, particularly ghosts, can manipulate the planar membrane to create visible and audible manifestations, or launch attacks from the ether into the material, but most effects from the ether are unable to pierce the membrane.
Ether vs. Shadow
The ether is also coexistent with the Shadow, which is as visible and audible as the material plane. Since the worlds bear a superficial resemblance and both are only vaguely visible, travelers may make several ethereal voyages before they realize that they are seeing more than just the material world through the fog.
Ethereal creatures are just barely visible from the Shadow as amorphous patches of light floating overhead. Occasionally, creatures from deeper in the Shadowlands will fly dexter into the ether at the sight of a particularly large or active bright patch. Spellcasters with the Transdimensional Spell feat may target these bright patches, but even then they are treated as having concealment (50% miss chance).