I'm pretty sure that this book is the last of a series. I only read the beginning.Based on the back-cover description, the story is set in another world that is populated by fantastic creatures. For some reason, I think the world is called "Neverland" or something that ends in "-land", but it's not a Peter Pan book. What I do remember is that there is a scene where a tribe or nation of fantasy creatures is invaded by another faction. The tribe that is being invaded is prone to entering a trance-like state when they see metal glinting, which is weaponized by their invaders (They carry poles that have bits of metal tied to them). The defenders try to resist the effects of metal glinting, but to no avail. That's pretty much everything I remember about this book. Any ideas what it is?
Other information that I think I remember about the book, but can't be considered reliable: There is some tree that is apparently considered important. The main character leaves that world to either go into what is considered the real world or some other world, either temporarily or permanently.