The aircraft carrier
You repeatedly jam the 'SHIELD' button as a block of solid metal (looks like tungsten, although it is hard to tell) folds out of your robots right arm. You move your right arm to shield yourself and the robot mirrors this as a long, echoing 'BOOOOM' cuts through the air. You feel your right arm jolted as the enormous metal plate blocks most of the railgun's bullet. The rest manages to make a small hole through the bottom, spraying shrapnel everywhere. Most of the remaining guards are knocked back from the shrapnel, no doubt with stories to tell if they ever get home.