This is honestly something I think they should update.
Spoilers
You need to do the White Witch quest. It takes you to another realm, where enemies are on par with your levels. What you need to do is this. You need to find a barrier removal spell, which is in a heavily trapped area on the map hidden in a mound. Use that to disable the barrier on the WW cottage, and proceed from there.
End Spoilers
This is one of the quests I really think that they should expand upon. I spent hours tormenting myself with higher level enemies because I had no idea about it. I had to come to the forums to figure it out as well.
