I wish you a nice night 
Reading in runequest forum a topic about pc visiting hells, it gave me the memory of my (kingdom of) ignorance
I m definitly not clear about the wonderhome :
- I understand that is a part of the underworld
- I understand the underworld is related with hell (the place of all the deads, not only the bad people)
So a dumb theory could be :
to please the trolls living on mundane world, you just have to kill them, the good trolls will go back the lost wonderhome
What is wrong then ?