Death Rays
Those of you who know your comic book history know that The Incredible Hulk was born when scientist Bruce Banner was caught in an explosion from a gamma bomb, or a bomb that emitted gamma radiation.

Well, today, munitions scientists are within striking distance of developing the real thing, through the use of the available high energy states, or nuclear isomers, of certain heavy elements, such as hafnium.

Using the technique described in this New Scientist article, a single gram of this stuff could be more explosive than 50 kilograms of TNT. And they would not necessarily be subject to the nuclear test ban treaty.