Geralt was racking his brains for a way to defeat Master Mirror when Shani came to his rescue. She knew of a professor from the Oxenfurt Academy who had spent years scrutinizing every manifestation of black magic and surely would be able to help. Unfortunately, the witch hunters had decided the professor's knowledge was best used for their goals and their goals only and had placed guards outside his home. Officially he was a free man, but in reality, no one entered or left the house without their permission.
The professor told Geralt of the long hours he had spent scouring old tomes for accounts of Gaunter O'Dimm, alias Master Mirror. He had been set on this trail by Olgierd von Everec, who paid him handsomely for his labors. This research had borne fruit in the form of a great many secrets abou the mysterious O'Dimm, including a possible way to outsmart him. Sadly, however, the professor did not live to see if this trick would work for Geralt in practice, for during their conversation Shakeslock made one step outside the runic circle drawn on the floor of his residence and died immediately. We will never know if this step was accidental or deliberate - by the time Geralt met him, he had become a tired and tormented wreck who just might have considered death a relief.