Death

Death eventually claims all creatures, large and small, but for some it is more inevitable than others. Mortals will eventually pass of old age even if all else goes well, but immortal beings will continue to live until something kills them; usually either violence or disease. Even the gods themselves can die, but this is an exceedingly rare occurrence. What happens to a creature upon their death depends on their origins, their beliefs, and sometimes even where they were at the time of their demise.

Mortals born on the Inner Planes

Those who die in the Inner Planes (most notably, the Prime Material Plane) arrive here shortly after their demise, where Olidammara's tour guides take stock of how they have lived their life and decide which of the Outer Planes they will pass on to. Usually religious creatures are sent to whichever plane their god lives on. Others are sorted according to their nature, so a good creature might go to Celestia or Ysgard, while an evil one might find themselves in Gehenna or The nine hells. Whatever the case, they first spend about ten days traveling through the Astral Sea before they can begin their afterlife proper. This is why spells such as raise dead need to be performed quickly; the farther a soul has traveled the harder it is to find and bring back to life. Creatures that have passed on to the outer planes in this way become immortal but are still entirely capable of dying again if violence or an unfortunate accident claims them. Usually those who die a second time become absorbed into the essence of the plane itself, but there are a few known exceptions like Ysgard, where the fallen simply rise again at the crack of down on the next day.

Mortals born in the elemental or outer planes

Mortal creatures born in the Elemental Planes (or more rarely, the Outer Planes) and die within their native plane will simply be absorbed back into their home plane and later become reincarnated as another being. Particularly religious creatures, however, or those which die outside of their native plane of existence, can sometimes find themselves in the Astral Plane, where they will be judged by Olidammara's tour guides. The guides may choose to simply send such a creature back to their home plane, or she might send them to one of the outer planes just as she would for mortals born in the inner planes.

Immortals born in the elemental or outer planes

The elemental and outer planes frequently house some immortal creatures that are native to the planes themselves. These creatures are usually called "Outsiders", since they were brought into existence within an outer plane. Examples include, but are not limited to, angels, demons, devils, yugoloths, and elementals. When an outsider dies outside of their home plane, they return to life on their native plane of existence with their memories in tact. For some creatures this process happens instantaneously and painlessly, but others must endure great suffering during their "rebirth". An outsider who dies within their own plane is absorbed back into the plane and later reincarnated as another creature, with no memory of their prior life.

Immortals born in the inner planes

It is extremely rare for an immortal creature to be born in the inner planes. Usually such a being was born by outsiders, in which case it follows the rules such an outsider would if they were born on their own plane. Other cases are so obscure that there is no consensus about what their fate will be.

Death of a god

Even the gods themselves can die, but the only known occurrences of this come from the previous era, and so not much is known about what actually happens. Scholars currently believe they would follow the normal rules for immortal beings, but they would not retain their power. Power of that magnitude has to go somewhere, but there are several theories about where it would go, and no real reason to believe one theory over another.