Okay, Wintertusk is old news now and so is the mystery with who the composer is.
Time to have him do something other than just stand there and conduct silver trumpet vines
How about a complex music themed quest spanning all worlds including grizzlehiem and wintertusk - all levels like Grizzlehiem is, broken into chunks you can get when you reach various levels+
You would get the quest start from the mystery composer outside Ambrose's at level 5 and the first part would be some where in wizard city.
Second part, get the start of it from the same mystery composer, level 10, some parts of the quest located in wizard city and some in krok
Third part, level 20, get the start of it from the same mystery composer, some parts located in krok, some in grizzlehiem
Forth part, level 30, get the start of it from Jonas in Grizzlehiem, some parts located in wizard city, some in krok, some in grizzlehiem, some in MB
Fifth part, level 40, get the start of it from Jonas, some parts located in wizard city, some in krok, some in grizlehiem, some in mb, some in ds
Sixth part, level 50, get the start of it from Jonas, some parts located in wizard city, some in krok, some in grizlehiem, some in mb, some in ds, some in Wintertusk
Last part, level 60 only, get the start of it from Jonas, some parts located in wizard city, some in krok, some in grizlehiem, some in mb, some in ds, some in Wintertusk, with conclusion being in a new, legend only dungeon.