Oveusly, a bomb with a timmer that can take out 3/38ths of a large earth sized city by amplifying its power with gamma radiation. Duuuuh, you would have to be a internet surch engine to not know that! No one knows what alien race was responsible for the invention of this terrible weapon loved by terrorist in hundreds of thousands of galaxies. But many nations, races, species, and empires have reversed designed their own versions of them. They can be carried as easily as a c-4. Note, for powerful bomb shelters thick enough to keep out the radiation, its still not a bunker buster.