Three figures stood on a muddy battlefield. The Doctor tilted his hat back, and looked apologetically at Sarah Jane and Harry.
"There's been a slight change in plan. This is Skaro-" he began.
There was a shrill whistling overhead, followed by the sound of explosions. Loud explosions, and they were coming closer.
"I say, that's gunfire!" said Harry.
"Heavy artillery," agreed the Doctor.
The explosions came on, marching across the ruined landscape like the thundering steps of giants.
"Doctor, it's getting closer," said Sarah anxiously.
"Creeping barrage," said the Doctor. A split-second decision: to get under cover or - "Run for it!"
They ran - and the world exploded white around them, as a shell made a direct hit. Harry and Sarah Jane were killed instantly. The Doctor, unfortunately, was not. His alien body fought to unite itself and regenerate, but the physical damage had been too extensive. Disease, trauma, even certain temporal energies could be overcome - but not being blown to flinders over a considerable portion of poisoned landscape. He did die. Eventually.
Three muddy Thal soldiers happened by later in the day, and were intrigued by the scraps of strange clothing and bits of curly hair they found. When one of them came up with the sonic screwdriver, all three of them agreed to bring it back to the Thal Dome. Perhaps they'd get a day of leave.
Not only did they not get a day's leave, they got hustled right back onto the battlefield along with a team of scientists who picked up every scrap of cloth, bone, and flesh that had once belonged to, or been a part of, the three travellers.
From the cells of the Doctor's body, the Thals learned regeneration. Troops that had come back from the battlefield maimed grew new limbs, new eyes, and returned to the battle with new vigour.
From the sonic screwdriver, they built weapons. Vibrational probes that detonated landmines at a distance. Resonance weapons that destroyed cell walls, turning the weapon's targets into screaming mush.
The Time Ring was the most powerful of the things they found. It had not disintegrated itself back into nothingness upon the Doctor's death, simply because it had not been triggered. They tested it, measured it, and carefully pried at its workings with their scanners. When the Time Lords finally got around to calling back the device, it vanished while under the minute observation of bank upon bank of scientific instrumentation. And from those instruments' readings, the Thals got time travel.
A spy had come in, and told the Thals that their supreme weapon, a rocket destined to smash the Kaled Dome and kill all within it, would be useless. The Dome had been coated with a substance that gave it the strength of thirty-foot-thick reinforced concrete. The spy was curious as to why the Thals were so interested in not how the coating could be destroyed, but when it had been applied.
The Thal rocket was finished and it launched - and vanished. Into the past, into a time before the Kaled Dome had been reinforced, it flashed out of nowhere and exploded, destroying the Dome and the Kaled people. The war was over.
Davros and the Kaled Elite, hidden in their Bunker, were helpless. The Dalek program would have been enough to save them - but it was too soon. They starved and they died, sealed away in the dark.
Absolute masters of their planet now, the Thals looked upon the ruins of Skaro, and were dissatisfied. They were paranoid about the alien artefacts that had been the key to their victory. What if the aliens were out there, right now? Waiting to pounce, to wipe them out!
The only way to be safe was to destroy them all.
Selective breeding over generations created Thal telepaths so powerful they could stop another's heart with a thought. Decades of experimentation created light, versatile capsules that could survive in almost any environment - and most importantly, could be hurtled through time and relative dimensions in space, and keep their passengers alive all the while.
The great day came: a day of rejoicing, of celebration. A crowd of celebrants, all waving ecstatically. A thousand Thal telepaths, dressed in their finest military garb, went into their capsules. The apparatus hummed, and golden flames of energy seemed to wave as well above the take-off field. Then the capsules were gone.
The capsules materialised, saturating the Universe from one end to the other, in both time and space. Inside each one, a Thal telepath, each one an example of the highest peak of mental power, equal even to an Osirian, thought one thought.
And on a billion worlds, every sentient being died. Their hearts pressed themselves flat; they threw themselves out windows or into machinery or under moving vehicles; they swallowed poison or water or air; they destroyed themselves and those around them with weapons or utensils or their bare hands/feet/tentacles. In a few hours, it was over. And sentient life had been wiped out of the Universe.
Back on Skaro, the Thal leaders gathered in their Council chambers, raised their glasses in a toast - and felt the death-grip close around their own hearts.
Foolish creatures! came the overwhelming thoughts of the telepaths. Disgusting, mind-blind little worms! Why should we share the universe with the likes of you? And the Thals, and their leaders, died as well.
Then came the Last War.
A thousand Thal telepaths. Each one raised from birth to hate all life, to be focussed on nothing but death for all that was not themselves. The breeding and conditioning program had succeeded far too well. Each telepath was consumed with the need to kill, kill all others, kill every thinking thing in the universe - including the other Thal telepaths.
There were a thousand at the beginning.
In the end, there was only one.
It would be supreme irony to have him die of a toothache or a head cold within the next year, but instead he piloted his capsule back to Skaro, and lived another two hundred years. And every day, he would wake up and kill another thing. His powers had grown so immense now that he could touch every world in the universe.
Butterflies, he would decide one day. Let every butterfly die! And throughout time and space, on every world, the brightly coloured flower-tasters known as butterflies (or the equivalent term in the local language that had, alas, died with the planet's inhabitants) would wither up and die.
And as he progressed up and down the chain of life at random, he left behind destroyed ecosystems. Plants ran riot after he killed all the grazers. Oceans poisoned themselves after he killed all the coral. Flowers rotted, seedless, after he killed all the bees. He left behind a universe filled with dying worlds.
And when he finally grew old and feeble, he would lie in his bed at the top of the Thal Dome, and stare out the window, and think warm and self-satisfied thoughts.
I did it, he would think.
I destroyed all other life forms in the Universe. My mind can feel nothing out there: nothing alive. I am alone, now, forever.
He died the happiest man in the universe.