Path to Godhood
The universe has multiple planes of existence; each plane has its own personality.
The Gods themselves exist in far planes in the outer sphere, where souls congregate after death. Traveling to these places, although extremely dangerous, could yield incredible knowledge and power.
All mortals have souls, which itself exists within the physical body. When the physical body erodes and dies, the soul flies off to travel through the astral plane towards the outer sphere, unless trapped by some work of magic.
But just because a soul doesn’t age, does not mean that it is safe from peril. Strange creatures of the astral plane prey on souls who stray too far from the silver stream that guides the way.
At the end of the stream is Boneyard, a place where the final destination of each soul is determine by the goddess of death.