Warworld
From superman.nu: Supermanica
Warworld
A fantastically dangerous planet-sized weapon created by an extinct race known as the Warzoons and taken over by Mongul after obtaining a key to its operation (DCCP No. 27, Nov 1980: "The Key That Unlocked Chaos!"). Though Mongul escapes, Supergirl manages to destroy Warworld by flying at super-speed straight through the battle-station's central core (DCCP No. 28, Dec 1980: "Warworld").