Veng the Manipulator is one of the most hideous enemies to mankind the world has ever known. His unique combination of Psionic abilities and magic items allow him to sneak into his victims dreams, and modify and direct the dreams, as well as “adjust memories”. Over the years, he has ‘programmed’ an insidious network of totally devoted followers. Using his natural ability of ‘Wisdom Drain’, he has created an army of willing slaves.
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.