PROSE: Engines of War

'I have done only what was necessary,' said Rassilon. 'What no one else was prepared to do. Borusa understood what was required of him. The possibility engine represents our salvation. With it, we might see the weave of all possible futures. We can choose our own destiny, selecting only the most fortuitous paths. We can measure the potential outcomes of all of our offensives against the Daleks. Ensuring our victory at every turn. We can bring an end to the War!'

[...]

'Tell me, Borusa, of the Tear of Isha. What is the true path to victory? How do I ensure its deployment strikes at the very heart of the Dalek cause?'
Karlax cringed at the sight of the possibility engine, cranked up on its metal bewd so that Rassilon might look upon it. To Karlax it was like a pale corpse, reinvigorated with life; emaciated, yet filled with a vitality that was not its own. The Time Vortex was running through its head, filling it with wonders and terrors beyond imagining. In the dim light of the tomb, it glowed with the aura of oscillating regenerative energy.
'The timelines are no longer clear to me,' mumbled Borusa. 'There is no true patth. Every outcome is in flux, and possibilities bloom. A random factor has been introduced which... unsettles things.'
'A random factor?' echoed Rassilon. 'What is it? The Dalek weapon?'
'No, my Lord. Something else. A knot of potential, moving unchecked through the timelines, weaving patterns in the future and the past.'

[...]

'What of the Doctor?' he ventured. 'He might yet attempt to prevent Commander Partheus from deploying the Tear.'
'Yes,' said Rassilon. 'The random factor.'