Warning, possible Star Wars spoilers ahead
The Lusankya is almost surely the most fascinating of the Executor-Class
Super Star Destroyers constructed by the
Galactic Empire. In order that it remain a complete secret, it was built at
Kuat Drive Yards under the name "
Executor", being the same name as an identical ship under construction by
Seinar Fleet Systems. Due to this, rebel intelligence completely failed to realise that there were in fact two ships, and merely thought that the claims of both shipyards to be behind the construction of the
Executor was the result of corporate pride.
After completion, the vessel was secreted away and renamed to the Lusankya. Following this, a huge area of Coruscant was razed, and the Lusankya buried under this area on a large bed of repulsorlift coils, only to be built on top of again. Despite such a massive engineering effort, this occurred when the Emperor was at the height of his power, such that through the use of his dark side powers he was capable of blinding the entire populace to this occurrence.
This permitted the Lusankya to be used as a top secret base of Imperial operations managed by Ysanne Isard. The Lusankya became infamous as an inescapable imperial prison where prisoners would be brainwashed and then sent on missions to assassinate their former friends. Indeed, so well hidden was it that Alliance Intelligence thought that the Lusankya was an asteroid prison somewhere in deep space. This was because the interior of the prison sections were built to appear like an asteroid mine, such that when interrogated after recapture, any brainwashed assassins could not identify that they were on a ship. In addition, the artificial gravity in the prison sections was reversed, such that were anyone to attempt to escape and reach the "surface", they would only be going deeper into the prison, assuring their capture.
Following the rebel capture of Coruscant, the Lusankya also served as a base for terrorist actions against the New Republic government. It was only discovered when Corran Horn, a member of Rogue Squadron captured and imprisoned aboard the vessel, managed to determine the true nature of the prison and escape. Once Ysanne Isard discovered that Corran had escaped, she ordered the Lusankya to lift off the surface. In tearing free, the Lusankya destroyed many square kilometers of extremely densely populated area, killing millions. It then proceeded to blast its way out of Coruscant's unprepared defences, and escape to the planet of Thyferra, where Ysanne Isard, with the help of the Xucphra bacta cartel, took control of the planet, gaining a monopoly on bacta production in the process.
Following this, Rogue Squadron (without the permission or support of the New Republic) engaged in a guerrilla war against Ysanne Isard. This culminated in a tremendous battle in orbit of Thyferra where the Lusankya was pitted against Rogue Squadron along with Thyferran freedom fighters, a fleet of retrofit freighters, an Alderaanian war cruiser, and the captured Imperial Star Destroyers Virulence and Freedom (originally the Avarice). Following a long battle, the Lusankya finally surrendered with massive damage. This marked the day the Lusankya passed from the hands of the Empire into those of the New Republic.
After some time, the Lusankya was finally placed into dry dock at the shipyards of Bilbringi, where the ship was given a complete overhaul, had its memory cores wiped, and had its prison cells replaced with research facilities. Eventually Ysanne Isard returned and attempted to recapture the Lusankya using secret computer access codes she had planted in the ship's computer systems during her ownership. However, this attempt was defeated when she fell into a trap laid by Rogue Squadron.
Despite being retrofit as a research facility, the Lusankya has also been involved in military action on behalf of the New Republic. It was commanded by Wedge Antilles in the defence of the planet Phaeda, and more notably in the defence of Coruscant against the Yuuzhan Vong invaders. While it was unsuccessful in defending the planet against capture, it withdrew to the world of Borleias, where the ship was had most of its weapons removed and placed on other ships. Finally, the gutted remains of the Lusankya were driven into the Yuuzhan Vong worldship, destroying it in a massive explosion. So ended the existence of the Lusankya, almost surely the most fascinating of the Super Star Destroyers, and definitely the one with the most varied history.
Note: The story of the Lusankya can primarily be found in the X-Wing series of Star Wars books, with its final end being found in "Rebel Stand" in the New Jedi Order series.