Veng the Manipulator is one of the most hideous enemies to mankind the world has ever known. His unique combination of Psionic abilities and magic items allow him to sneak into his victims dreams, and modify and direct the dreams, as well as “adjust memories”. Over the years, he has ‘programmed’ an insidious network of totally devoted followers. Using his natural ability of ‘Wisdom Drain’, he has created an army of willing slaves.
You receive a vision of a rooftop "somewhere close by", where a rare moss grows; in the vision, you know the moss is suitable for greatly enhancing the effects of certain types of potions. Now go and find that rooftop. Don't fall off. (Of course, rooftop runners *will* be taken for miscreants by the local City Watch....)