Templar or Marauder sword and board tempest shield. Need to evaluate the ascendancy classes though guardian looks the best candidate for auras/additional block.
EDIT: wanting to be a fire/lighting based "caster", is it safe to mix the two types of damage? Explaining better - i'd like to have two main sources of damage to have less issues with X immune bosses/monsters, but i don't know if the investment would be too great to make it work.