Inevitable
What little that living intelligent peoples know about the Inevitable comes from the words of the Deities. It's common knowledge that the Inevitable is where creatures go after they die, as well as that ordinary methods of scrying aren't capable of viewing whatever it contains, but aside from that, the plane is shrouded in mystery.
Geography
The segments of the Inevitable that can be viewed by the Deities of Higher Shenzala appear to be a blend between environments from the Middle and Higher Realms. The portions visible to the Deities of Lower Shenzala seem to resemble a mix of Lower and Middle Realm geography. Individuals have traveled far enough into the parts of the plane unseen by any Deities that they surely know what the landscape is like there, but if they return, they are unable to communicate what they've seen to anyone outside the Inevitable due to the Realm's magical barriers.
Localized Phenomena
Each intelligent being who perishes in another Realm is transported here at the moment of their death. Whether they want to go or not doesn't matter. Here, their facets of consciousness are transmuted and they gain properties similar to those of the Deities (particularly the ability to regenerate from major wounds and the power to shape small portions of their environments.) They no longer need to eat and do not age. Interestingly enough, where a person is deposited within the plane upon their death depends on their actions and moral compass before they died. People aligned with chaos are pulled to the lower-altitude portions of the Inevitable and those aligned with order find themselves closer to the higher-altitude areas.
The Inevitable's boundaries are protected by a magical seal with multiple effects. The first is the blockage of every known scrying spell used by the intelligent races, preventing them from knowing what lies within the Inevitable's bounds. The second is a barrier preventing living creatures from crossing into the plane. Many have tried to catch a glimpse of the Inevitable for themselves, notably including the now-elementally-dismembered Kore Tazuka, but none have been successful. Several brave souls have also attempted to physically cross over into the plane, but those attempts were also fruitless.
Climate
The climate ranges from mild to harsh, depending on the altitude of the portion in question. The mid-altitude areas are theorized to be moderate in weather and temperature (though the only ones who know for sure are the dead creatures who've traveled there themselves.
Fauna & Flora
Non-self-aware creatures that were loved by an intelligent person seem to be able to follow their loved ones into the Inevitable. Many a reunion between a beloved dog and its master has been witnessed by the Deities.
Tourism
Travel to the Inevitable from outside Realms seems to be impossible, but travel within the Inevitable is common. People regularly move around within its bounds in search of loved ones who've passed on before them (or simply to explore.)
