Nightmare Dimension
by Giulio CarolettiThe Nightmare Dimension is an Outer Plane of Existence or maybe even an other Dimension, with no relationship with the Multiverse. The Nightmare Dimension is inhabited by a great number of extremely strange creatures, and is build upon a totally different geometry and mathematic system, which has no resemblance to our three dimensional space.
It is not, however, the home plane of the Diaboli. The Diaboli dwell either in one Abyssal plane or in a Prime Material World that is built on a different biological structure (maybe not even carbonium based). The Nightmare Dimension features a different number of dimensions. Where the Prime Worlds and most of the Planes are three-dimensional, the Nightmare dimension and its creatures live with a different number of dimensions. The actual number of dimensions varies from creature to creature: the dimension allows its creatures to form themselves on different mathematical criteria, even one from the other; this explains their incredible differences in structure, behaviour and molecular composition, and even the existence, in some of these creatures, of elements not known in the Multiverse.
This fact is particularly significant if applied to the studying of corpses from the Nightmare dimension that were found dead in our Prime Material Plane (the number of reports and information on these happenings is so rare that it's better not to rely completely on our theories): many of the organs of Nightmare creatures seem completely useless here, and sometimes it seems that they lack sensorial organs that belong to our Plane, or even the case of alien organs that work in the same way as ours, although bearing astonishing differences (this is particularly true for Neh-Thallgu's way of vocal communicating through internal organ that had clearly NOT this function originally).
The real essence of the Nightmare dimension is still unknown, because only through dreams and astral-travelling-like spells has it been possible to travel through these lands. It is supposed that some Dream Master from Glantri have been able to combine these abilities and travel astrally in the Nightmare dimension, but it is still uncertain how they realised that, and many wizards don't dare try more than once this power, due to the horrific and totally different geometry of the plane in relation with what we are normally used to.
It seems that crazy sentient beings of the Prime Plane sometimes can 'tune' in some way with the Nightmare dimension, and the same can be done with specially suited variants of high level magic spells (as the 9th level spell Gate, although it is uncertain which changes are needed for the exact Gate to open). The atrocities these discoveries lead to, caused by the more evil and cunning of the creatures of the Plane normally drive totally over the edge the minds of these poor souls.
Sages speculate that the Nightmare dimension is simply one of the layers of the Abyss, but this remains doubly true due to the totally different aspect of the creatures found in the Nightmare dimension. The Nightmare dimension is also believed, by recent studies, to be the home plane of the Evil Elemental Power, the Dark God Tharizdun, and of most (if not all) of the Outer Beings and their servants.
It is still unknown exactly WHY
these dark powers want to enter the Prime Plane and don't content
themselves with the plane where they originated, but maybe the way
of logic in a so different world would be anyway lost to human
compression.