What is the Astral Plane?
The Astral Plane is the world of spirits without bodies, the realm of the mind. It is the realm of ideas, and here the Gods generally feel most at home. Here intelligence, wisdom and charisma replace strength, dexterity, and constitution. The Astral Plane contains and keeps separate all splinter realms. Through the Astral Plane, the Solar Hearth can be approached. The Astral Plane often reflects the minds of those in the Shards: a surge of religious fervor can create storms of dogma in the Astral Plane, while the despair of a Rising can plague the Astral Plane with swarms of fear and fluttering neuroses.
What is the Ethereal Plane?
The Ethereal Plane is the realm of embodied spirits, and is sometimes called the Spirit World. It is the ghostly reflection of all the Shards. It covers the material world of the True Creation, yet in ways is the past and future echo of it. In the Ethereal Plane, time can at times flow strangely, and visions of the what will be or has been sometimes shroud the Ethereal. A temple that will fall in the near future might be seen ruined and desecrated in the Ethereal. Many beings can enter the Ethereal at will, having weaker ties to the material world.
Outsiders and the Splinter Realms.
Splinter realms are believed to be some of the first creations of Õemag as he prepared himself for the masterwork that ended his being: the Shards. The splinter realms are partially formed planes and semi-worlds that can be connected by their lack of perfection.
All splinter realms are missing some essential thing that the races of the Shards take for granted. The splinter realm of the devils of the lost city of Vezanti lacks joy, mercy, and hope. Other splinter realms are missing truth, death, individuality, and so forth. All splinter realms seem to feel lacking to those who live within them, or who venture within their bounds. There is a palpable yet vague feeling of something being 'missing'. For this reason, natives of the splinter realms covet the True Creation of the Shards, yet their presence often perverts that which they seek to embrace. Like a sponge, their lack of a quality drains it from the world around them when they venture afield. For this reason, such outsiders are considered dangerous to reality, though often such outsiders are more immediately dangerous due to their lack of morality, goodness, or compassion.
Many splinter realms have been catalogued by the Pentatra, though there are almost certainly others that have as yet to be discovered. Some splinter realms can be reach via gates or weak points where they come close to our plane. Others are completely cut off, though situations or circumstances can come about that create a channel from the True Creation to the splinter realm. It is known that at least some splinter realms have some connection and commerce with other similar realms.
A few of the splinter realms:
Khantavra is the Realm of fiery spirits of the air, the djinna and efreet, whom Chaltis created long ago. They won their freedom from her long ago, but never have escaped their home for any great length of time. They know only fire and emotion, and never satisfaction or reflection.
Abdysos is a one of many realms of demons. Those of Abdysos, however, seem to place great stock in the worth of the soul, since that is what they lack. They are more inclined to deal with thinking peoples through trickery or intrigue.
The Screaming Spires: a place of infinite torment, the Screaming Spires is another demon realm. The revel in pain, and know nothing but loathing for themselves and others. Light is also unknown is the Screaming Spires.
Hrymantha is an uninhabited splinter that knows no need, sadness or regret. Those that enter are often loath to leave, for to all appearances it is a paradise. Hrymantha is somehow alive and aware, and lusts after inhabitants. It can sometimes intersect with the Shards, and attempt to lure people into its plane. Those who enter are without any past fears or personal demons, and even regretful murderers can find peace within it. The downside is that left to their own devices, the blissful inhabitants will forget to eat and drink, and slowly waste away with contented smiles on their faces.
What is magic?
All magic in some way connects with the secret workings of the world, formerly the sole domain of the gods. The gods originally shared the knowledge of these 'cosmic laws' with their chosen when they left the Shards to dwell in the Solar Hearth. To affect the unseen and tamper with the architecture of creation was a last gift to their followers.
Divine magic is an innate knowledge of these secret workings of the universe, with changes applied through divine will or divine consent. Such direct will or second hand consent (such as those spells cast by a cleric) are powered by positive energy to create their effects. Positive energy is generally an extropic force, a source of energy and power without source. Such displays are often accompanied by a halo of pure light, which varies in color from god to god.
The exception to this is the 'divine' spells of the Beneath and its scions, which accomplish the same ends through innate knowledge of the fabric of the universe, powered by an unwholesome will to destruction, more commonly known as negative energy. This is anti-creative force, and even though things can be created by clerics of the Beneath, they are always in some fashion tainted by the negative energy used to power the effect.
Arcane magic was created through careful study of the divine spellcasters. It has discovered much of the secret workings of the universe left by the Creator God, but has no positive energy to power effects. Instead, elemental energy or energy close to the caster is used to access the loopholes in creation left by Õemag. There are some feats that arcane magic is limited in, but it does not require faith and wisdom to sense the cosmic tools of creation and channel divine energy through them. Instead, only intelligence and dedication to strict formulae and established techniques are required to pantomime the god's might and tweak the cosmic laws.
Psionic power is a more personal form of magic, and perhaps is more akin to the manner in which Õemag first created things. Psionic power calls upon the same cosmic laws, but rather than call upon external reserves of power from the gods or nature, the psionic individual substitutes their will and inner harmony for positive energy. They quite literally force the cosmic laws to do their bidding though force of mind.
Ki power, as practiced by the various monastic orders across the Shards, is very similar to psionic power. It draws upon inner strength, but from a trained intuitive aspect rather than by mental strength. Ki users draw upon their own life-energy to power their relatively modest feats and tamper with the cosmic laws that exist behind mundane reality.
Anti-magic fields and so forth sunder the connection between a spell user and the cosmic tools they rely upon to change the world. They enforce a normalcy, removing all cosmic tampering whether the source be divine, arcane, psionic, or ki.