Is using a tree as a door to a world beneath our own too overdone/stupid? There are several trees all across the world, and they are guarded by a particular kind of demon. To use the door and get into the world, you need to have a pass, and those demons are the only ones that can open them. This is the one part of my story where I'm currently clueless. I'm not sure how big a part this will play yet either. I've been thinking of other things as well, but I feel like whatever it is, it's been done to death.