World Devastators were incredible planetary assault weapons that were used by the revived Emperor Palpatine when he attempted to retake control of the galaxy. World Devastators, like the Death Stars that preceded them, were more than weapons of mass destruction. They were symbols of the Empire's ability to utterly destroy any being or any world that would stand in its way.
World Devastators did not destroy planets. Instead, tractor beams drew a planet's surface into a molecular furnace, which broke the components down into ray materials. These materials were used in the World Devastator's droid-controlled factories. As the World Devastator chewed up a target world, that world's resources were used to create new weapons.
World Devastators utilized hyperdrives and ion engines for transport in deep space, but their main role was to devour a planet's surface. The central droid brain controlled the onboard factories and stored plans for Imperial war vessels—a World Devastator could produce TIE fighters, battle cruisers, or even other World Devastators. During the Battle of Calamari, the World Devastators produced automated TIE/D fighters in large quantities.
The World Devastator "grew" by consuming planets and asteroids: some materials were devoted to building new additions and expansions for the Devastator itself. The Devastator's droid brain could create custom additions and alterations, so no two "mature" World Devastators were identical.
The Silencer-7 was the largest World Devastator built and led the assault on Mon Calamari. At 3,200 meters long and 1,500 meters tall, it was larger than an Imperial Star Destroyer and had a crew of 25,000 beings. The Silencer-7 could take on any target, with 125 heavy turbolasers, 200 blaster cannons, 80 proton missile tubes, 15 ion cannons, and 15 tractor-beam projectors.
The key to the defeat of the World Devastators was Palpatine's fear that these weapons could be turned against him. Palpatine created a command and control coding system that allowed him to seize control of them at any time. The New Republic was saved when Luke Skywalker provided these signals to R2-D2, who shut down the World Devastators on Mon Calamari, allowing the New Republic's forces to utterly destroy the helpless planet smashers.