Note: This trick requires the Cowbell Skull enabled. Start at rally point bravo. and get a ghost after you go to the big hole in the ground with the two Wraiths. After killing everyone, a small door should open into the tower. Push the Ghost in by beating it, then take the Ghost through the doors until the game saves and the Scarab walks over you. Get out, throw a plasma grenade on the Ghost, and jump. You should land on the Scarab. This may require some practice. Get in the turret, wait until it sinks into the ground, and get off. Kill it and run away. Continue with the level and when the time comes, only half of a Scarab will come down.