The second part of Albus" plan was rather unexpected. The idea had come to him after his first interactions with Quirrell after his return from Albania, it had been during this meeting that Quirrell had first expressed an interest in the Defence position. He had figured out that Quirrell was working for Tom, the later realisation of their closer relationship had come later. Using the protection around the stone as a test of Tom's current state. Each one made to see how badly damaged he had been and how close he was to full strength.