Proton Accelerator Gun
The Proton Accelerator Gun was a super-weapon designed during the Terran-Kilrathi War. Initially developed by the Kilrathi Empire and later adapted for use on vessels from the Terran Confederation, it was a massive cannon with the capability of destroying large-scale enemy targets. Depending on the variant and the user, it could destroy heavy warships or even entire planets.
In 2654, the Kilrathi tested their prototype Proton Accelerator Gun (also known as the Graviton Weapon) on Warhammer XII. The weapon fires a special explosive burst (similar in appearance to a Particle Cannon blast) at a target, and the explosion is followed by a 137 fold increase in gravity, which completely eliminates a target. The weapon went on to form the centerline armament of the Kilrathi Sivar dreadnought, and was field-tested with the complete destruction of Goddard Colony. The Kilrathi weapon had a single operational drawback: it took several minutes to lock and fire, making it ineffective against capital ships and other mobile targets.
The Proton Accelerator Gun proved to be highly effective for the Kilrathi at Goddard: All 250,000 Terran citizens and all other lifeforms inhabiting the planet were killed, and every settlement on the surface was reduced to utter ruin. However, it put a major power drain on the Sivar, forcing it and its strike force to retreat to Kilrathi space so that it may be reloaded and refueled. The Sivar and its signature Proton Accelerator Gun were eventually destroyed by pilots of the TCS Tiger's Claw during a covert operation to destroy the super-weapon, and the technology was lost to the Kilrathi.
However, the wreckage of the Proton Accelerator Gun was extensively studied by the Confederation, and by the 2660s was redesigned as the Phase-Transit Cannon. Unlike the Kilrathi version which was limited to the destruction of planets, the Confederation version was instead revised as an anti-ship platform, and it became the centerpiece of the iconic Confederation-Class Dreadnoughts. Its only drawback was its drain on the reactor of said dreadnoughts, and if fired more than once within a short time frame could trigger a catastrophic overload of the vessel's power plant, forcing the Confederation to limit its use in a single engagement. However, it proved to be a valuable weapon, and was capable of annihilating virtually any Kilrathi warship with a single blast.