The Devil is a Time Traveller, or The Duvan'Ku Retcon

"You must understand, our presence here doesn't alter history. You and I meet here because we are compelled to, we have always met here. History is irredeemable. Drop a stone into a rushing river, the current simply courses around it and flows on as if the obstruction were never there. You and I are pebbles, Raziel, and have even less hope of disrupting the time-stream. The continuum of history is simply too strong, too resilient."

-Kain, Legacy of Kain: Soul Reaver 2

"And as of that moment, he was gone, he got sucked in and he was zapped out of the past, present, and future, out of our memories. They have that power somehow, whoever 'they' are. But one night, me and John got really drunk and we sat around telling Todd Brinkmeyer stories, real stories, stories that happened but didn’t happen. I think of his face and sometimes I can see it, and it’s like a dream you can’t quite remember the next morning. And I go back and go over the chain of events and there’s places, holes where I know Todd should be. He was there and he helped us, Arnie. He fought with us. And I’m not even allowed to remember him, to mourn his death. At least Jim got a funeral. But Todd, I can’t find his picture in the yearbook. Can you even imagine what that’s like?"

-David Wong, John Dies at the End

(This pertains to my Lamentations of the Fall Lords setting based on the Myth video game series.)

Most mages don't grasp this, but necromancy is just a sub-school of chronomancy. You turn back time on the capabilities of rotting flesh and bleached bone without restoring the warmth, the physical wholeness in space, the smell and pulse of true biological life. You reverse time unevenly, to create something that is dead in the present yet acts like its living self in the past. Sometimes, in proportion to your skill and knowlege, you augment the past/present not-corpse/corpse as desired, with abilities it could have had in stillborn timelines. You give it flight from the universe in which it had bladders under its skin full of lighter-than-air gas, or energy-draining powers from the non-past in which it was a creature of the negative material plane.

If none of this makes sense to you, you're probably not a necromancer. Even if you are a necromancer, you might not understand this.

If a teacup falls on the floor and shatters, one could repair it with a localized time-reversal spell. Using necromancy, one could imbue a shard of that teacup with some of the properties of the entire, full teacup. Pour tea on it and the liquid would float in the air, contained by invisible boundaries, the ghost of the teacup. Anything you can do to a teacup, you can do to a human body. A ghost is not a soul, it's an incomplete reversal of time. An animated corpse is just animated by part of its former self.

So if necromancy is just chronomancy, why did the Fallen Lords show such a complete lack of imagination? Why attempt to conquer the world with slow, stupid, destructible armies of undead when they could have turned the bodies of their enemies into super-heated gas from moments after the big bang, or turned their enemies' food supplies back into seeds, soil, water, and sunlight? The Fallen Lords were masters of necromancy, so why apply it only to mere meat?

Because necromancy did not always work this way. Or rather, it did always work this way, but only because history was changed retroactively.

The Duvan'Ku were, depending on which place and time you're talking about, either a religion or a nation or a school of magic or a secret society or a species or a boogeyman or a demon or a god or all of the above. The facts that remain constant are these: they are evil, they worship death and all its attendant miseries, their power comes from the manipulation of death via the manipulation of time, and they work to insert themselves into the histories of as many worlds in as many universes as possible.

The Duvan'Ku did not always exist in the Myth universe. When the Cycle was broken (or delayed, depending on who you ask) at the end of the Soulblighter War, the world lost some of its insulation from the other worlds in the multiverse. Alien beings and foreign magic began to immigrate to the Myth world in a slow trickle, sometimes unwillingly and sometimes on purpose. This is why Elves never existed here and then suddenly the Cath Bruig Empire was lousy with the bastards. This is why everybody and their grandmother seems to know Magic Missile when wizards used to be rare and Magic Missile was just an anagram for Miss Cilia Gem, former Duchess of Madrigal.

But unlike the other newcomers, the Duvan'Ku had the power to insinuate themselves into the world's history retroactively, so that they were always here. They're only newcomers from a metatime perspective.

To an outside observer of both the original and Duvan'Ku-influenced versions of the Myth world's history, things will be mostly the same on the surface (the flow of history is not easily diverted, after all), but subtle changes can be observed, changes which may eventually create a vastly different future when they all add up. The insidious stain of the Duvan'Ku now marks previously-unconnected events.

In the old timeline, the Fallen Lords didn't use chronomancy because necromancy and chronomancy were completely different disciplines in the Myth world, working through mostly-unrelated principles of magic. A ghost was the soul of a dead person, not a trick of time manipulation. The Duvan'Ku altered the metaphysics of the world, the fundamental fabric of local magic, the very rules of how magic works, to create an environment more conducive to their schemes. The effort of such a monumental change killed the Duvan'Ku (or at least these Duvan'Ku), but that matters little to masters of death and time.

But as mighty as the Duvan'Ku are, history is mightier still. It could not be changed all at once. In the new timeline, the Fallen Lords waged their wars in almost exactly the same manner, due to sheer chronological inertia. If you asked them why they relied on animated skeletons to do their dirty work, they would probably laugh at your boldness and then kill you where you stand, but assuming they didn't do that they would probably cite some obscure magical problem that made the flashier necromancy spells more trouble than they would be worth. "Equivalent exchange" or something.

But in the year 2841 A.E., magic seems to be easier to use, more eager to be cast. A new Fallen Lord might not face the same difficulty, assuming they could obtain or create the right spells.

And the Duvan'Ku, though long dead, once reveled in the certainty that their unfathomable, sadistic plan would inevitably turn a bright future into calamitous fate.