Few travelers deign to enter this layer but for pilgrims of the lords of the Abyss, as it represents one of the worst horrors inflicted by the tanar'ri on the celestials of the Upper. Deep in the distant past, during the dawning days of the Blood War, a collection of tanar'ri posing as risen fiends spoke with twelve devas, each a representative of one of the most powerful deities of the Upper Planes. They beseeched these angels to come to the Abyss, to help rescue others of their kind held prisoner for reindoctrination by their betters. In these early days, when many more celestials than today held out hope for a nonviolent end to the Blood War, their tale touched the hearts of these twelve, and they agreed to follow the tanar'ri in under cover of spell, blinded by their hope for redemption of these fiends and their desire to find a means to potentially end the bloodshed raging across the Lower.
There, they found a vast, desolate plain, a deep purple sky stretching above and red, loose soil stretching beneath, the only sign of life being a ring of twelve towering dryad trees transplanted from the depths of Arborea stretching hundreds of feet above the ground, twisted by dark magics and fed the blood of their own dryads, a slow bleed over the course of twelve years before their lives finally expired. Within moments they each realized there was no prison camp to be found in this lifeless expanse, but their realization came too late, as the last step of the dark ritual was completed by their willing entrance onto the Abyss. The trees themselves reached out for the devas in an instant, seeking out their divine essences as a replacement for the loss deep within their heartwood. With the aid of the tanar'ri and their ritual, the devas were bound within the trees, not living yet not dead, their spiritual essence leaking from the trees like sap as their endless, deathless screams began to shriek across the entire layer, never ceasing for even a moment in all the days since then.
The power of this ritual granted this layer its position as a place of power for the tanar'ri. Shortly after, a basalt platform was installed in the center of the ring of trees, the power of the sacrifice of the devas allowing other great and twisted acts to be performed here. From transformation rituals to enchantments to divinations to communions, tanar'ri from across the Abyss began exploiting the layer for any number of purposes; it quickly became the closest thing to a holy site the demons have.
Twelvetrees is, for obvious reasons, extremely deadly to any traveler not sworn to the Abyss, and as such, few reports of it from those not associated to the tanar'ri are known. Even so, it was the twelfth layer to be recorded in the Lexicon of the Abyss, discovered by a small collection of aasimon that are among the few outsiders to have looked upon it and survived. It was placed under immediate interdiction by the Fraternity of Order, and no known portals to it outside Pazunia have been recorded. What is known is the constant tortured cries of the twelve devas render essentially all speech and hearing impossible, requiring telepathy or sign language for communication on the plane. Even more, it's only the most steeled souls that can resist the plaintive tones of the wails and moans for long; few with any degree of empathy towards others can last through the emotional torment for long.
Anyone on the layer is treated as though incurably deaf, with all associated penalties. Further, any Disguise checks on Twelvetrees to pose as a tanar'ri or Abyssal pilgrim must be checked every ten minutes; this check starts without penalty, and for every ten minutes on the plane this penalty increases by -2, as the individual finds fending off the impact of the screams of the devas increasingly difficult. This penalty and requirement for constant rechecking may be waived at DM's discretion depending on the nature of the character involved.
- Fiendish Codex I, pp.134-135
- In the Abyss, pg.31
- Planes of Chaos - Book of Chaos, pg.20