The World Ash defines Creation, its upper leaves in Heaven and its roots in Hell. The worlds of the universe hang in its branches like fruit grown ripe from the Angelic Light above. The Ash is surrounded by a cylindrical Weirding Wall that separates Creation from the Outside (from whence come the Excrucians). It is said that there are eight ways through (or around) the Wall, but these pathways are only known by a few.
Chancels (the little pocket universes that Imperators create, from which they wage the War) are not technically on the Ash or on Earth. The Imperator takes a location (usually from Earth, but always from a world on the Ash, not the Ash itself) and "removes" it from its place in reality, anchoring it to his home on the Ash so it does not become lost. It is possible to walk between the Imperator's Chancel and the Imperator's home on the Ash, but usually only with the Imperator's guidance.
Known alternatively as the Otz Chaim or Tree of Life, the World Ash is no metaphor -- it is an immense physical (well, spiritual) thing which holds Creation in place. All realms can be reached by travelling the Ash, from the Houses of Heaven atop the tree to the Decans of the Lords at the very edge of the branches; even the rogue Planets claimed by the Fallen Angels must pass among the branches at regular intervals. Upon the trunk of the Ash, one finds two of the factions in the War:
The Aaron's Serpents are embodiments of nature and physicality. Leagues in length, miles in width, a Serpent on the move could devour a small town without even slowing. The original guardians of the Tree, since the beginning of time, they abhor fire and saw, and demand respect for that which embodies Creation. The ten kings of the Serpents are known as the Sephiroth, and their kingdoms within the tree form a journey from Malkuth, at the base, to Kether, whose realm adjoins Heaven.
The paths between the Sephirothic Realms are officially unclaimed territory -- in truth, each path has been forged into a demenses by a True God. "True God" is not so much a type of Imperator as it is a catch-all for beings that are neither Celestial, Lords, or Serpent. Each True God is a unique being with its own outlook and beliefs, bound to the other True Gods by ties of diplomacy, rivalry, blood, and occasionally marriage. The greatest of the True Gods make up the Major Arcana, two and a score that lay claim to the greatest "between" realms within the Ash and nominally speak for the others.
Should one ascend to the very top of the Tree, a massive Gate bars the way. Were a visitor somehow able to talk the Angel who guards it into letting him inside, the glory within would fill the senses with such unearthly joy and rapture that all time would be forgotten and all previous desires cast away. However Mortals, and even Nobles, have been deemed unfit to enter such a place of beauty, and are invariably turned away. The Angels are too busy constantly changing Heaven (for beauty cannot be static) to baby-sit lesser beings. Even the Nobles who serve under an Angel are never permitted within Heaven proper; the Angel's home within Heaven will always include a door outside of the Gate where the Nobles will emerge.
The Angels within Heaven are judgmental, yet justifiably so. For it was they who crafted all of Creation, using flowers as their tool, and it is thus they who are allowed to decide what is Just and what is Beautiful. The Angels are divided into a strict hierarchy, with a dozen Archangels at the top. These Archangels each maintain a Zodiacal House along the circumference of Heaven, which shines its light down upon the entire Ash as all of Heaven rotates above it, bringing it life and energy.
At the very bottom of the Otz Chaim lies Hell, home of the Fallen Angels. Its roots penetrate deep into the shadowed realm, feeding on the suffering and pain therein. Hell has four eschelons. At the lowest rank are the humans, toys for the depraved, corrupt demons which make up the next rank. Above the demons are the Fallen Angels, still indescribably beautiful and magnificent, entities of vast power, yet still trapped within Hell by the far greater forces of Heaven. Above all others is Lucifer, whose uncorrupted vision guides all of the Fallen.
Though charged by Heaven to remain trapped in Hell forever, some Fallen Angels have found an escape. The seven Planetary Spheres which orbit in spirals around the Ash are each inescapably linked to one of the Seven Sins. By infernal right, a Fallen Angel may claim one of these spheres as his fiefdom, and thus an extension of Hell -- gaining access once again to all of the realms upon the Ash. The Angels allow this "loophole", but forbid any of these Fallen Angels (or Heptarchs) from leaving their domains, upon penalty of death.
A cylinder of beautiful blue flame, the Weirding Wall defines the very boundaries of Creation. From a distance, it appears uniform, but as one approaches it, it becomes obvious that it is segemted, its 360 degrees separated into 10-degree bands, known as Decans (from the Greek decanos, meaning "ruler of ten"). As Heaven rotates, the light from its Houses shines down upon different parts of the Wall; as Hell's Planets orbit the Ash, this energy is warped by conflict. This conflict between Houses and Planets determines where the Decans rest at any given moment on the Weirding Wall. As the alignments of Heaven and Hell change, so do the Decans shift, subtley trading places and rearranging themselves to avoid upsetting the balance of Creation.
The inhabitants of these 36 Decans are the Lords -- a trinity of factions that appeared when mankind first learned of Good and Evil. One third are the Lords of the Light, created when Eve first learned of Humanity's greatest destiny; they struggle to keep Man alive and well through whatever means necessary, even if that means his stagnation and imprisonment. Another third are the Lords of the Dark, created when Adam first realized the dark fate to which Humanity could succumb; they wish nothing more than for Man to destroy himself, and push Humanity to advance beyond its limits and to embrace nihilism. The middle third are the Lords of the Wild, a pure embodiment of the choice that Man has between these paths; they throw off all pretense of sanity or mundanity and believe that no man should be beholden to any other, for any reason.
The ruling twelve Lords of each faction claim one of the Decans as home, invariably building an empire just above the middle of the Wall, where the branches of the World Ash scrape against it. This allows them access to the Tree and other Realms, though which branch is available at any given time depends upon the movements of the Houses and Planets above.