Within the pages of this ancient and dusty tomb are the blueprints of the mad creations of a powerful Lich.
This frightening creature has some rather cruel methods to torture its prey
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....)