Certainty is less secure at boundaries, reality less rigid. In places ambiguous (neither sea nor shore, day or night, river or land) magic can seep through.
Work in Progress
Lindsay Buroker has a space opera series that I am enjoying a lot. The characters are well developed and interesting. So far there are five books in the Star Kingdom series: Shockwave, Ship of Ruin, Hero Code, Crossfire, Gate Quest. I am looking forward to the next one.