The Kurasian superweapon was a device designed by the original inhabitants of the world Kuras IV. During the final stages of their technological development, they began to experience rapid growth in all scientific areas, including the development of weapons. This was the last device to be developed by them prior to their extinction, and is presumed to have caused that extinction.
The device seems to cause, by some means, an entire planet to freeze or enter some kind of ice age over a short period. It is unclear whether this is the primary purpose of the device or a side effect, since its properties have not been studied in detail. It is, however, quite clear that the device could be used to turn entire worlds into frozen tundra, causing the extinction of many species and the limitation of many more.