WordNet sense 1 (a criminal who illegally sets fire to property):

arsonist, firebug

WordNet sense 2 (a bomb that is designed to start fires; is most effective against flammable targets (such as fuel)):

firebomb, incendiary bomb

WordNet sense 3 (arousing to action or rebellion):

inflammatory, rabble-rousing, seditious, incitive, instigative

WordNet sense 4 (serving or tending to provoke, excite, or stimulate; stimulating discussion or exciting controversy):

provocative