Defend from about 2000 supply of all 3 races, air and ground. Build up your defenses for 15 minutes(It takes 1/4 the time to build units and building and SCVs, Probes, Drones, and buildings have 4 times more life than normal. You start out with an extra SCV, Probe, and Drone. Each time you destroy 5 prisons, you get another SCV, Probe, and Drone up to 10 times. 3 waves of enemies come attacking your base with 5 minute intervals after the 15 minute mark. Defend your base for 30 minutes.