In a previous timeline, this battle turned out in the favour of the Time Lords, who were able to prevent the Daleks from taking the Cruciform, but after the Master used the Heavenly Paradigm to alter the timeline, an unforeseen consequence of his meddling lead to the outcome of the battle being a Dalek victory, allowing the Dalek Emperor to take control of the Cruciform. (AUDIO: The Heavenly Paradigm) The Master, horrified by his actions, ran away and used a Chameleon Arch to turn himself into a human infant and hide near the end of the universe. (TV: The Sound of Drums; AUDIO: The Heavenly Paradigm)
Behind the scenes
The Cruciform has not been confirmed to be either a location, a weapon, a ship or some kind of object. It has only been mentioned, not described. The word "cruciform" means “cross-shaped”, and is, amongst other things, a type of real-life screwdriver.