The Last Great Time War: part III

Prologue: the First Great Time War

Author's note: If you want this to make sense, please read the previous parts of my story. Thank you!

Based on an excerpt from the Black Scrolls of Rassilon, as translated by [name redacted], also known as the Doctor, the Warrior, the Renegade, et cetera. The portion upon which this was based was the last to be translated.

Rassilon strode through the hall of his private fortress in the Death Zone, with two guards flanking him. His cloak cast a long, flickering shadow over the dark stone in the torchlight. He carefully ascended a flight of stairs with his elegant, deadly new treasure.

He reached the door to the highest room and ordered the guards to leave.
The room was cavernous, medieval, and beautiful in its own way. Resplendent banners hung from the ceiling, illuminated by burning braziers. Beyond a pair of small obelisks was an altar about the length of a man.

After centuries of fighting, Rassilon and the Time Lords were nearing total victory. Most other time travelers were exterminated, and few serious challengers remained. The main enemy, the King of Time, was no more. He was utterly annihilated from reality. There was not a single parallel universe or timeline in which he existed.

However, there were still many species who possessed crude time travel technology or were on the verge of gaining it. If left unchecked, they could eventually become a serious threat. Rassilon could not allow any threats to his world and his position as Supreme Ruler of the Gallifreyan Empire and soon to be ruler of all creation.

This was why Rassilon and his top minds created the thing which he was now placing on the table. Never before had Rassilon and his people created such and intricate and ambitious project, nor would they ever do so again. This was the final work of ultimate sophistication and complexity, the culmination all Time Lord secrets and knowledge. Its incredible mechanics and workings were interwoven and infused with the time vortex itself, bonded with the undercurrent of reality in a secret manner that would soon be lost forever. All the power of time and space flowed through it in a way that would not be replicated.
This was the Final Moment of Victory and Ultimate Annihilation, the most powerful and destructive weapon ever constructed. It was also known as the "Galaxy Eater," but even that told only a small fraction of its true capacity. No one had tested it, so it was impossible to be certain, but it was probably capable of annihilating the whole universe or more.

Its appearance was somewhat underwhelming and deceiving. It was not a cannon the length of a galactic arm, a bomb the size of a star system, or a station as big as a galaxy.
Instead, it was a cube less than a meter across. Its surface was inlaid with brass clockwork and elaborate circular Gallifreyan writing. There was no switch or button. Only Rassilon knew exactly how to use it.

As Rassilon was putting the command into the Moment, he heard a noise.

"Intruder, show yourself now," he commanded, looking around the room. "If you do not, your death will not be painless!"

"You wouldn't kill me, old friend," said a voice that Rassilon never thought he would hear again.

He spun around and saw none other than his best friend and collaborator Omega sitting by the Moment!

"Omega," Rassilon exclaimed. "You're alive! How did you escape the supernova?! I must hear all about it!"

"We have more important matters at hand," said Omega. "Are you sure you want to use this terrible device? Wipe out countless innocent lives?"

"They are not innocent," said Rassilon. "They are potential threats, and must be eliminated before that potential is realized."

"You never know what people are truly capable of unless you give them a chance."