Every sentient mind generates a small psychic field (called a soul), which contains its thoughts, emotions and will. In a living being, this field is bound into the tissues of the body. When the body dies, the soul dissipates.  (Or departs for another plane of existence, depending on your point of view.)  Such is the natural order of things.

Occasionally, a person learns to manipulate the latent power of their souls � these are the magicians, the psychics, and the mediums of many worlds. Their powers are minor, usually so minor that they are overlooked in the general order of things, and their very existence often doubted.

Similarly, it is possible for a soul to remain in the physical world after death. Such a disembodied soul strains its will to maintain its presence in the living world, to hold back its memories and personalities in the face of the entropic dissipation. Inevitably, only the strongest personalities survive, becoming a ghosts, only partially self-aware, and frittering away the centuries  repeating the same obsessive actions until it fades away. Ghosts are generally so rare and weak that many people do not even believe that they exist.

So it is in most worlds, but on some world, somewhere, a minor magician at some time, made a terrible discovery. In the interval between death and the departure of the spirit, the psychic energy of the recently deceased may be harnessed. The window of opportunity is short, usually only a few moments long, but in that time, a magician can use the dead person�s soul to cast a spell considerably more potent than the magician can cast on his own. The dying soul wails in agony as the magician rapes it of its personality, its will, and its memories, and funnels those energies towards a new goal.

Once the local magicians uncovered this secret, they rapidly gained control of states, then nations. Sacrifices became part of their ritual, and these sacrifices become ever larger to provide even more energy. It might have gone no further.  Indeed, legends say that for thousands of years terrible thaumatocracies of blood and instant gratification dominated the face of many worlds.

The ancestors of the Ka�Tash, however, learned a yet more potent secret: that of soul bonding, a ritual which can permanently link two souls. When one soul dies, regardless of distance or desire, it will travel to its partnered soul and there be absorbed. By itself, this technique is of little use. A bodied soul is not free to absorb its bound partner, and both participants risk madness, possession or death. A properly prepared object, however, can contain multiple souls. Most magicians know that souls can be forced into physical objects, in which their departure from the physical realm may be infinitely postponed, but do not find it particularly useful except as a means of punishing their enemies. Yet the Ka�Tash saw the use of Soul Bondage: the creation of a Pylon.

To make a Pylon, the magician binds his soul to that of a chosen victim, which he has already placed into a suitable object (usually a large stone). From that point forward, the magician may draw the energies of the trapped soul to himself across any distance or even from another world. If he desires more energy he need only bind more souls into his Pylon. The process is infinitely scaleable; a suitably prepared Pylon can hold thousands, even millions of souls. A magician with a Pylon commands power without limit --- at a price. On death, his soul too is sucked into the Pylon, there to mingle with the other souls until it is destroyed. Yet even the most powerful magician can only channel so much power at a time, but a circle of magicians working in concert, and drawing on the enormous reservoirs of the engine can produce truly prodigious effects.