A Complete Guide to the Cosmos - The Dimensional Nature of Beings
by Giulio CarolettiUnliving things have just dimensions 1 to 3, or 5 to 3 if they are in the Mirror Tetraspace. If taken from one Tetraspace to the other, they simply change their nature to fit the new dimensions.
Living mortal creatures have all dimensions 1 to 4. They are not able to perceive their 4th dimension, but they can somehow "draw" upon this dimension to cast magic or to use magical effects, in different ways.
This ability can be reflected in magical special abilities, in psionics, or in the skill to learn Arcane Magic. Priests are granted the ability to cast Divine Magic by their divine protectors.
In the Mirror dimension this becomes living in dimensions 2 to 5, but being unable to perceive the 2nd, with almost the identical skill to cast magic.
If a living mortal creature passes from one Tetraspace to another, it suffers great pain during the transit, because it must change all its dimensional physical nature.
Mortals can attain Immortality, which means that they discover how to use some of their 4th dimensional abilities and become able to perceive it.
Immortals and Athanatoi exist at levels 1 to 4, and are able to use some of their 4th dimensional abilities, and to perceive all of it.
Immortality is thus just a major stage of evolution of mortality, however it is very difficult to attain.
Immortals can cross the boundary between the Tetraspaces. They too suffer the dimensional change; moreover, in the other Tetraspace they lose their Immortal status, because here they are simply mortal, not having learned to use their 2nd dimension in Mirror Shape (or vice versa, if crossing to Normal from Mirror). Returning to their home Tetraspace allow them to regain their Immortal status. Athanatoi, on the other hand, cannot cross the boundary (only with a mortal manifestation of their power - this is an Avatar in AD&D 2E Game, or a Mortal Form in D&D Immortals Rules).
True Gods and Mirror Gods exist in all 5 the dimensions, however they have been permanently cut off their 5th dimension when the two Tetraspaces were generated (maybe by the Old Ones, but who knows? Surely not the True Gods). There is no way for them to regain the lost dimension, but they can perceive and use fully all their 4-dimensional skills, and this explains their powers in the Tetraspace. Contrarily to all the above-mentioned creatures, they cannot cross the boundary between a Tetraspace and the other; however, they could, with a terrible expense of power, cross directly the Inner Vortex from a Multiverse to the other (although they really do not have the need to do so, as they usually keep at least an Immortal Identity in each Multiverse). A True God's Immortal Identity, however, can pass into the Mirror Tetraspace (see above).
Ulterior Ones exist in all five dimensions, but have been "cut away" from one of their "inner" dimensions (that means 2,3 or 4), separating part of their essence in one of the Tetraspaces and one in the other.
This has prevented them to be the only living creatures still able to live in both Tetraspaces simultaneously, something that would give them total control over the Cosmos. The Athanatoi, True Gods and Mirror Gods are responsible of this imprisonment, but the fact that it is not "natural" could mean that one day or another the Ulterior Ones may eventually have the upper hand over the powers that bind them and regain their complete freedom...and thus dominate the Cosmos...