Good thinking, but the only other element types we know are Green (Thorn, Eris Morn, etc) and Red (Crimson Double's Ability) element types. Possibly a Time/Pure Light element like the Vex Gate effect or Hardlight. If we add in a single new element type for the Fourth Class, would it's other two subclasses be existing element types, or would each Class receive a fourth Subclass as well?