Two creatures, forever cycling between the phases of the 5 elements, unable to rejoin.
The unnatural offspring of a zombie father and a human mother.
The excited, almost frantic sound of a mallet instrument erupts from the forest to your left. Within minutes, your party is confronted by a host of short, sprite-like gnomes clad in vivid greens and earthy browns. Attempts to communicate fall flat. The gnomes seem to ignore your words entirely, and you cannot understand the humming/whistling/snapping that apparently makes up their language. Luckily for you and your fellows, however, they don't seem hostile . . .
When you sleep, your soul briefly returns to the place where it was created/goes to when it dies, and seeks nourishment. Everybody's soul is created with a little link (or you could say a greater entity calls it back) to that place so that it can return easily, but upon death, the soul returns via that and annihilates the link as if returns.
Also, as an added thingy, you could say the entity supplying the link, or residue of the links themselves, (whichever) is the source of all arcane power.