The voidstone reveals a vision of a multi-story building haunted by ghostly figures.  As the scene sharpens and blurs, other buildings come into view, leading you to believe it is Goldenmist Village.$b$bRooftops and tree canopies suddenly flash by, revealing the way to Goldenmist by following the Elrendar River to the west.$b$bOnce there, use the voidstone near the rune of summoning atop the center building and defeat the summoned voidwalker.  Only then can you return to your teacher.