From GameWatcher: “But the rarest class is the Demolitionist Character Class, as it’s not available at the start on the free-to-play version of the game. So what is the Demolition character class and how do I get Demolitionist in Defiance 2050? We’ll show you – although you might not like the answers.”
Source: N4G PC Defiance 2050 – How To Get The Demolitionist Class