This achievement can be earned in a solo or multiplayer (local or online) game of Contractions. The easiest scenario is "Mechanized Invasion." You will need to reach wave 7 until deep fog covers the ground; you'll know it's deep fog when you see red lights floating across the ground. In the preparation phase (before the fog), jump in the Powered Armor and spend the entire wave killing enemies. If you cannot get the Powered Armor or are in a different scenario, be sure to not stand in the red lights, as they will hurt you and can force you into Last Stand.