this form of Yuuzhan Vong starship was developed during their attempt to take control of the galaxy. Its development came shortly after the New Republic learned to pour intense amounts of firepower into a dovin basal, weakening the creature and stealing power from weapons systems. In this way, the Republic managed to destroy a number of Yuuzhan Vong warships. The keeper was well-protected, and contained a large dovin basal. The keeper was the attached to another, larger, Yuuzhan Vong warship, to act as its shielding and protection. In this way, the larger ship was protected from enemy fire by a stronger shield, and their weapons didn't lose power when the shield were absorbing fire.