Win a ranked multiplayer game on all maps (gametype not important).

All you have to do is play elimination for the smaller maps, play conquer all for all the bigs maps. Also just choose high tech and go in and out of a territory for the control takes. In the settings before making game you can adjust taking time to almost 0. Trade back and forth with a friend until all maps are done. In the mean time, you can also get the "Test Drive the New Toys" cheeve by finding the new weapons to kill each other with. This must be ranked so just find each other's rooms.