This is a Castle Wall puzzle.
One difficulty I have in constructing Castle Wall is that the inside/outside clue information often plays a fairly trivial role. I tried to do a lot more with it here. Consequently, this one is rather tough.
Also, this is advance notice that Puzzle 400 won’t be anything too special. The kind of energy I need to create a large/complex milestone puzzle is being channeled into the packs and next year’s mystery hunt. Speaking of packs, volume 3 is likely to be out in the next couple of weeks.