Requires the completion of the quest "There's a First Time for Everyone" from Mederiel in Lake Shiverwave. I also had to complete the last dungeon of Rohendel "Phantom Palace", and then talk to the queen to unlock this quest. Happy questing!

To get Mederiel's Guitar, you need to kill the Frenzied Giant Flame Construct in the waypointed area

This quest begins in Rothun where you have accepted the previous quests for this line right next to the piano.