The Diamond Eye of Korr

From Introduction:

Many years ago, an old, venerable wizard lay dying alone in his small thatch house. Wise and kind, the wizard had made many friends in his life, yet none were at his side in his last hour. The reason for this is not entirely proven to be known, but rumor has it that the elderly mage had posed a quest to those that adored him.

He told them a tale of yet another wizard, this one very dark and evil. Supposedly, this dark wizard owned a large diamond that he referred to as the Eye of Korr. With this diamond, the evil mage could scry into the minds of any he wished, and manipulate his victim’s thoughts.