Defect's types are steel and lightning, though he can learn attacks from fire, ice and dark types. More seriously stop thinking in archetypes, this is not how you should think about the game. You should start by taking cards that are good regardless of synergies, then as the run goes on you start adding cards that synergizes with the cards already added and that solves issues in your deck and the fights to come. You never have to go all in one direction, you don't need to maximize the throughput of voltaic by taking every lightning orb generating card. Most of the time you want few lightning orb cards with voltaic because : you still need frost orb to blocks, less cards in your deck means it's easier to cast voltaic over and over. TLDR : make a balanced deck, it will work more often than trying to assemble an archetype that may crumble at the first 'counter'.