She became an absolute ruler by taking control of the life drink supply and rationing it. Later, she decided to conquer Earth with her army of Saurian Evolutionaries and kill all other Gandorans, whom she considered imperfect, as they were not genetically engineered as she was. When the Second Doctor and Jamie referred to the Saurians as Ice Warriors, Zaadur liked the term and renamed them as such.
She later killed Veltreena with an overdose of the life drink. She then had the Evolutionaries kill all the Gandorans. Zaadur then launched her rocket, unaware that Risor had stowed away. Risor, wanting revenge for Veltreena's death, blew up the rocket, killing himself, Zaadur and the Evolutionaries. (AUDIO: Lords of the Red Planet)