The A'rthans left behind many artifacts of immense power. The greatest concentration of these artifacts currently known is an A'rthan Shipyard, which fell for a time into the hands of the Shyedarians during the Shyedarian Revolution. Although the Shyedarians were not able to gain control over most of the technology in the Shipyard, one object they did take over was a gigantic artifact ship which they nicknamed the Planetsmasher.
The Planetsmasher's original purpose is unknown, but to the Shyedarians, it looked like a perfect weapon of war: its main armament was a mass driver that could hurl huge spheres of depleted uranium with enough energy to crack the outer mantle of a planet. The ship had no working drive system when it was found, so the Shyedarians attached their own hyperspace drive to it. Although its hull was impregnable to all known weapons, it had no other offensive or defensive weapons, so it was accompanied by a fleet of Shyedarian warships for support. The Empire's first goal for the Planetsmasher was to destroy the Shedarian homeworld, which they had tried unsuccessfully to conquer twice in the past.
The Rebellion learned of the Planetsmasher's approach, and organized a planetwide evacuation of Shedar IV, using A'rthan transport gates provided by Sol Karichee to move the entire population inside the Dysonsphere. Fortunately for the Shedarians, the Planetsmasher never reached Shedar IV: Sol Karichee, assisted by Zraki, managed to intercept the Planetsmasher and disable the Planetsmasher's added Shyedarian drive system, halting its advance. He also made contact with the ship's A'rthan AI system, freeing it from Shyedarian control.
The Planetsmasher has since been returned to the A'rthan Shipyard, where it remains dormant, watched over by the HKorjorans.