My brother and I have been searching for a young adult book for some time that we read as children (in the late 90's). The book is solidly fantasy and involves significant instant spacial travel (like teleportation but magical and not in a sci-fi way).
The main scene that I recall is a girl (one of the main characters, teenage or younger) being chased up a stone tower by a sort of humanoid creature. She falls after reaching the top but I forget what causes this. I specifically remember that the tower is located in a large field of wheat and that she (and the assailant) "teleported" to the location before climbing the tower. The book also describes her not being harmed by the fall due to her unconsciousness when she hits the ground (like a drunk driver not being harmed by a crash because they stay relaxed).
Another scene that MAY be from the same book is they visit an island with a large city on it and a neighboring island has an antagonist character who has his mouth sown shut.
I recall tidbits else but am really not sure if they are from the same book. I do not know if the book is part of a series either.