Come! Enter into the safe haven beneath the seas! Where humanity fled from the deadly Kalleum bombs! Take Refuge Beneath the Waves.
You think the zombies are bad? Wait till you meet their masters!
A bloated corpse shows up downriver from a Taoist monastery. Brought to you by
the words bloat, corpse, redhead, Tao, monastery, murder, underwater treasure,
chains, Wuxia, and romance.
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.