From the edge of existence, the angel of death materialized over the great city between the walled mountains.
   Iro heard the combined roar of a million soldiers as it pirouetted toward the battle, past burning arrows and boulders rising from the siege engines. Along the boulevards raced swarms of horsemen. The nearby hills held the enormous tents of the Grecians, attacking the Chou capitol with their Visigoth and Mongol allies.
Every second of the intervention had been planned and budgeted.
   Unseen in the chaos, Iro took prisoners for interrogation and brainwashing. Soldiers from both sides vanished when no one was looking.
   This was Iro's 19th intervention in this subset. It had visited countless other versions of Earth, slowly evolving into a 99% flawless Temporal Editor.
   Unable to correct human nature, Iro still marshaled vast energies. Sweeping through the potentialities, its timegun could kill ten thousand tyrants per second.
But new timelines emerged every Planck second and were immediately lost. It was an uphill struggle against tribalism and the religion virus. Overseers only altered the most promising 'butterfly points' of maximum leverage.
   As the towers and ramparts vanished behind smoke and fire, Iro dropped diamond-coated Guides for the survivors, and buried a Time Egg that would eventually hatch into a copy of itself.
The carnage would serve its purpose. This battle would link the great empires of East and West, perhaps someday leading to the best of all worlds.
   Within minutes its useful work was done. Ignoring the refugees streaming from the killing fields, Iro blinked back into imaginary space.
During the journey to its next intervention, it had a few seconds to think freely. Iro suspected most interventions failed.
   It didn't matter. As long as somewhere there was one perfect reality.