A great idea for a product! That's something I could use.
While I like the sound of the product and likely will get it, what I find disappointing is that it doesn't deal with non-terrain powers. That is, building an encounter involving an interesting terrain - like say, a clockwork room with these mechanics, or the various rooms in Pyramid of Shadows (like the water tubes) etc etc. Basically a guide to help design an entire "room" with different elements.