simple as this...you are a fire character, in order to be a successful burst to get most exp, PURE STR fires are the best, my alt has the same str as me and iam lvl 1XX. he is lvl 29. anyways the point is str determines how much exp you can get, the more damage you do to the enemy, the more exp you will get...i get 45k most of the time with my main burst group.