Research Heavy Electro Cannons, AA Rocket Launchers,
and Sonic Cannons as high as they will go, along with the Heavy
Defense building. Now line the area you want to defend with Laser
Walls and place a single Guardian defense structure. First, place
two Heavy Electro Cannons down. Next, put two Sonic Cannons on
top of these. Next to this, place two Nests each with an AA Rocket
Launcher on top. Also, the LC has the best shields in the game
so be sure to use them. For added defense, put some artillery
in the area. Also be sure to place an SDI when fighting against
the ED!