When the great ice-sheets covered the north, life retreated before them, but some species stayed and endured. Whilst man huddled around fires in his caves, mighty beasts roamed the tundra: the Woolly Mammoth, the Woolly Rhinoceros…and the Woolly Wyvern.
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....)