Green Lantern: Rise of the Manhunters

To get this achievement you need to defeat a giant robot that has (spoiler) Kilowag inside of it. The ring will tell you that you need to hit its knees to knock it down, then you need to use a powerful move to hit the center piece.

What I did was spam the rocket launcher so that both sides of both knees (4 weak points) all received damage, once they go from a solid color to slightly on fire and electrified switch to throwing hover mines at each of the four weak points, when it drops to one knee go to the front of the robot and hit it with the Jet construct (or whatever you feel is powerful). Rinse and repeat until the robots health is at 1%.
When the robot is down to 1% and you drop him for the last time you have to jump then attack the center piece in order to finish him.

Note: as the enemy's health drop little manhunters will join in the fight.