ChopRaider is in the fourth set of Special Ops missions that you unlock. You unlock it by finishing all five of the Vidar missions in conquest. the map is shaped to create an image of a helicopter and is a reference to Whiteboard War, a game created by Virgil Wall that has you flying a helicopter destroying enemies. the map has a very weak creeper emitter on the helicopter and a devastating amount of spores.
Strategy Step by Step: