A fragment of the shattered medallion is all that I can offer.$B$BYou must find another of dragon blood willing to assist you in forging a new key. Once you secure this key, you must travel to the Wyrmbog in Dustwallow Marsh. It is there that you will find her lair, $N.$B$BWhere to find other flights willing to help? Sadly, I do not know... They are said to exist. Some may even work and live among us, disguised as one of the humanoid races. I wish you luck.
