What does the Hexagon Key do?
The hexagon key is meant to get you into moonlit tunnel in the Hobbe cave. But it was soon taken out of that role. This was because the quest where you get the hexagon key is optional and you have to visit the cave after, if you didn’t do the optional quest you would have never got the key and couldn’t have progresses. My solution to this would have been to make the Hobbe cave quest a core quest and not just an optional one. But there way is good as well.