That is an excellent song for this list. Nice catch. I actually don't have that album. Gonna have to get it.
This list actually use to be strictly instrumental. I eventually started adding favorite slow songs. I had to add some Rachmaninoff and the Fleshgod piano instrumentals to the list just now. If anyone knows any metal piano (or any solo instrument, really) instrumentals, it'd be awesome if you can list it here.