cp_grack is a 5cp map, designed specifically for 6vs6 play.
As I am entering beta stage right now, I'm trying to get more publicity toward the map, and get it tested on a broader userbase. As of the beta release, it has been tested in a bunch of double mixes, and I adjusted it accordingly.
The newest release and more info can always be found on it's tf2maps.net thread, although I will try and keep this one updated.: