Moment Thirty-six
They were the most dangerous weapons in the Universe, so dangerous that the Time Lord High Council had sealed them away. Their use was strictly forbidden and, apart from the Demat Gun (which the Doctor had once recreated and used against the Sontarans) none of them had ever been used. Until now . . .
The Time Lords, desperate for victory in the Time War, had resorted to using the Forbidden Weapons. The Demat Gun, which erased its victims from existence; Omegarite, an explosive so powerful that even a few micrograms could vaporise an entire Dalek fleet; the Temporal Accelerator, which caused time within the target area to speed up . . . The latter was uncomfortably similar to the Time Destructor with which the Daleks had once tried to conquer the Universe, but there were now factions among the Time Lords who believed the use of virtually any weapon was justified in a war such as this.
So all the weapons in the Omega Arsenal had been used against the Daleks at some point. All of them except one. There was a device, known simply as the Moment, which could destroy an entire world and everything on it, a device so powerful that its operating system had developed a conscience. In effect, the Moment could sit in judgement on anyone who used it - and how could you use such a destructive weapon when it could do something like that? Even the Time Lords, desperate for victory as they were, dared not take the risk.
But the Doctor knew there was no other way. For the sake of all creation, the Time War had to end and the Moment was the only thing that could bring the conflict to a decisive conclusion. The only way to stop the endless cycle of destruction was to destroy both warring races. So he had stolen the Moment and made off into the desert with it, fully intending to use it. No more - the words echoed in his mind. No more Daleks. No more Time Lords. No more Time War.
He recalled the time, early in his fourth incarnation, when he had been sent on a mission to destroy the Daleks at the point of their creation. But, when the time came, he found he couldn't bring himself to do it. If he wiped out a whole lifeform, even one as evil as the Daleks, he would be no better than those he was destroying. His hesitation had ultimately led to the failure of the mission - though the Daleks were entombed in the Kaled Bunker, he knew they wouldn't stay entombed - and it also led to the war which now threatened to destroy everything.
This time, the Doctor knew, things must be different; he must not hesitate to do what must be done. The endless nightmare that was the Time War had gone on for long enough. And many races now regarded the Time Lords as little better than the Daleks. Cass, the young woman he had tried to rescue from her doomed spaceship, had made that all too clear. At any other time, she might have become his latest companion; instead, she had refused to let him help her and died when her craft crashed on the planet Karn.
The Doctor had barely survived the crash and, with the help of his old allies from the Sisterhood of Karn, he regenerated into his current incarnation. An incarnation he would later spend centuries denying ever existed. But at present he had no intention of even surviving; as far as he was concerned, he was on a suicide mission.
As he made his way deeper into the desert, he told himself that he was doing what had to be done. The very nature of the Time War meant the whole Universe was threatened as long as the conflict went on. Already, several of the Lesser Species had been caught in the crossfire, their worlds destroyed as the Daleks and the Time Lords fought to obliterate each other. No more. He had held back for too long - it was time to end it once and for all.
He had spelt the words out with gunfire on the wall of a ruined building. No more.