This is the Cyborg boss. I used a very easy way together with two friends.
The easiest way is to M5-32 HAV, the Heavy APC, in co-op. One person can drive and the other can shoot the vehicle's anti-tank weapon. The third person on foot can support where necessary and distract the boss.
Keep driving in circles around the boss, avoiding his attacks, and destroy the jammers where possible. After you're out of ammo, use the next one. As long as the gunner doesn't miss all the time four APC's are more than enough to destroy the boss. You'll probably only need two.
After the boss is dead, this achievement will unlock.