Hey guys, just some input.  I got some displacement shader plugged into a bunch of functions doing some pretty cool stuff.  I just don't want that cool stuff creeping up the mountains in the background.  Unfortunately, I can't help but notice that there's no way to blend displacement shaders via masks or anything, leaving me trying to find a wacky workaround.
So, just sayin'
Displacement, blend by shader, together one day.