She decided that the only way to hide from the War was for the planet to be boring. To that end, she "processed" all the brightest minds on the planet, turning some of them into her masked, brain-dead "blank squad" while tracking down and eliminating others.
She wanted to process the Doctor in order to make him less interesting. When she attempted to break the Doctor during a live broadcast, however, the Doctor was able to break her instead after easily being able to resist what she was trying to do, forcing her to admit what she had done to her people and why she had done it, leaving her to be eliminated by her own blank squad before the Doctor shut them down. (AUDIO: Planet X)