It is indeed a plasma, the most complex plasma imaginable. It is created by ionising the gas Mehium, M3Hi, and once a single molecule of Mehium has been ionised a chain reaction is started causing all of the Mehium in the world to ionise and the destruction of the world. However, when contained within the fist of the M3Hi the reaction can be controlled just enough to stop it running out of control.
Damn true.
Forgot to mention; the power of controlling a highly un-stable plasma was actually first harnessed by one PurcupineJim who suceeded in controlling the 'almost-as-lethal-as-Mehium' power of the compound Jimium in the year 1247. PorcupineJim passed on his knowledge of controlling dangerous ionic plasmas to M3Hi who successfully harnessed Mehium.