The Astral Plane

It is the space between everything.
It is the road that goes everywhere.
It is where you are when you aren’t anywhere else.
The Astral Plane is the space between the planes. When a character moves through an interplanar portal or projects her spirit to a different plane of existence, then she travels through the Astral Plane. Even spells that allow instantaneous movement across a plane, such as dimension door, briefly touch the Astral Plane. The Astral Plane is a great, endless sphere of clear silvery sky, both above and below. Large tube-shaped clouds slowly coil into the distance, some appearing like thunderheads and others looking like immobile tornadoes of gray wind. There are occasional bits of solid matter here, but most of the Astral Plane is an endless, open domain.

Movement in the Astral Plane

The Astral Plane's lack of gravity makes it a tricky place to get around in. Most of the plane's inhabitants move by merely thinking themselves in a particular direction. This is akin to flight with perfect maneuverability and a maximum speed of 10 feet per point of Intelligence. When one is maneuvering through astral space, “up” and “down” are determined solely by the traveler's orientation (down is beyond your feet, and up is above your head). Unlike normal flying, climbs and dives on the Astral plane don't change a character's speed, and there's no minimum speed to avoid a stall.
An astral character may double move, but his maneuverability drops to average. An astral character may move at four times his speed (effectively running), but maneuverability drops to clumsy.
Individuals with an Intelligence of 0 or without a listed Intelligence score (golems, for example) can move very slowly, and then only by pushing off other solid objects. Their maximum speed is 10 feet, and they cannot double move or run. If they are somehow grounded by localized gravity and able to walk, they move normally.

Creatures of the Astral Plane

The Astral Plane has few native forms. It does have a lot of travelers, and some natives of other planes have taken up permanent residence there. The most notable of the “almost natives” are the githyanki, a race that long ago fled their mind flayer masters and established their own tyranny almost as bloodthirsty as that of their illithid enslavers. The astral dreadnought may be a form of native life, but that creature's origin is difficult to study.
Travelers may be encountered either in physical form or in astral form. In the latter case, travelers appear as ghostly, silvery images of themselves. A silver cord trails behind each one for a few feet, then disappears into the astral haze. In general, an astral form is more dangerous than a physical one, because it takes a high level of magical proficiency to cast an astral projection spell (as opposed to just casting plane shift).

Githyanki on the Astral Plane

The githyanki live on the Astral Plane in cities, fortresses, and citadels. These cities are built upon large pieces of dirt and rock afloat within the vast emptiness of the Astral Plane.
Compared to the communities of most other races, githyanki communities are very militaristic in nature. Though they do not live in barracks, their homes and businesses are arranged according to the rank and standing of each individual or training group. Githyanki do not arrange themselves into families, but instead identify themselves by the training groups they belong to. Training is one of the most important githyanki values, and it rarely ceases. Each githyanki strives to excel over his or her companions.
Training centers, magical laboratories, libraries, and practice fields are the most frequented portions of any githyanki community.
Tu'narath: Tu'narath is the largest and greatest githyanki city. Subjective directional gravity holds sway within 200 feet of the stony form, allowing the city's inhabitants to walk around normally. Tu'narath boasts a githyanki population of about 100,000. The city is also cosmopolitan enough to host other races in their own quarters: humans and a few fiendish races.

Locations and Features of the Astral Plane

The Astral Plane's lack of gravity makes it a tricky place to get around in. Most of the plane's inhabitants move by merely thinking themselves in a particular direction. This is akin to flight with perfect maneuverability and a maximum speed of 10 feet per point of Intelligence. When one is maneuvering through astral space, “up” and “down” are determined solely by the traveler's orientation (down is beyond your feet, and up is above your head). Unlike normal flying, climbs and dives on the Astral plane don't change a character's speed, and there's no minimum speed to avoid a stall. An astral character may double move, but his maneuverability drops to average. An astral character may move at four times his speed (effectively running), but maneuverability drops to clumsy. Individuals with an Intelligence of 0 or without a listed Intelligence score (golems, for example) can move very slowly, and then only by pushing off other solid objects. Their maximum speed is 10 feet, and they cannot double move or run. If they are somehow grounded by localized gravity and able to walk, they move normally. Distances are deceptive on the Astral Plane, and maps are almost completely useless in the hazy expanse. The time it takes an individual or a group of individuals to reach a particular part of the Astral Plane depends on how familiar the travelers are with that area.
"Very familiar" describes a place the traveler has been to very often and feels at home with. It takes 2d6 hours to reach.
"Studied carefully" is a well-known place from regular visits. It takes 1d6 x 6 hours to reach.
"Seen casually" is a place known from occasional visits. It take 1d6 x 10 hours to reach.
"Viewed once" is for a place seen one time only, or a place that has been seen only by magic. It take 1d6 x 20 hours to reach.
"Description only" can be verbal or written, although a map to the location would be useless on a plane so devoid of landmarks. It take 1d10 x 50 hours to reach.
Travelers on the Astral Plane suffer no movement penalty for armor or weight, but they can carry no more than a heavy load while moving.
Movement through the Astral Plane is silent.

Silver Cord

An astral form may always return to its original body as a standard action. Severing the silver cord that connects the form to the main body kills an astral traveler's normal body. The cord usually appears at the base of an individual's skull and stretches back 5 feet before merging with the Astral Plane. Only a few circumstances, such as the psychic wind, an attack from an astral dreadnought, or a blow from a powerful githyanki sword, can sever this cord. In this case the normally insubstantial cord is treated as a tangible object with the owner's AC, hardness 10, and 20 hit points. Monsters, items, and circumstances cannot sever a silver cord unless this ability is specifically noted. An astral traveler is automatically aware if his or her silver cord is threatened—but not automatically warned if his or her original body is threatened, so many leave guardians or spells to protect the original body or alert the owner if something threatens it.

Psychic Storms

There are winds in the Astral Plane, but they do not usually affect the astral traveler. Clothing and hair tends to flutter backward during astral travel, but rarely do the psychic winds blow more strongly than a light breeze. But occasionally, the Astral Plane flares up into a psychic storm that whips through the area, delaying travelers or driving them onto other planes. Psychic storms may also affect the minds of travelers. The storm itself usually brews up without warning. The Astral Plane darkens in one direction, and the darkness quickly engulfs everything in its path. Only those who move directly away from a psychic storm at a speed of 320 feet can outrun it. Others are overtaken by the storm. Those caught within the grip of a psychic wind might be blown off course and suffer mentally from the psychic turbulence of the storm. Though they are violent, psychic storms have consistent winds, so several travelers caught in the same psychic storm are blown to the same destination.

Astral Objects

Bits of solid matter are strewn through the Astral Plane. Most of these objects have been sucked through portals or left behind by careless (or deceased) adventurers. It's easy for travelers to spot such items (subject to the usual maximum vision range) and maneuver toward them. Natives of the Astral Plane, in particular the githyanki, often sail the astral winds looking for bits of debris to add to their own fortresses and hoards.

Traits

No Gravity: Those traveling through it move by thought (see below). Objects and creatures with no Intelligence score cannot move in the Astral Plane, though they may be pushed.
Timeless: Age, hunger, thirst, poison, and natural healing don't function in the Astral Plane, though they resume functioning when the traveler leaves the Astral Plane.
Infinite Size.
Alterable Morphic.
No Elemental or Energy Traits: Some small regions on the plane may have one or more of these traits, but the plane as a whole does not.
Mildly Neutral-Aligned.
Enhanced Magic: All spells and spell-like abilities used within the astral may be employed as if they were improved by the Quicken Spell feat. Already quickened spells and spell-like abilities are unaffected, as are spells from magic items. Spells so quickened are still prepared and cast at their unmodified level. As with the Quicken Spell feat, only one quickened spell can be cast per round.