Based on theory, it is to let the system know that a low lvl lvling, while the fastest atker will be decide to be the 1 who gain exp. So lv1 pet (lower lvl than the mobs u wanna burst) and with high spd (horse, ofcoz if u cant lower ur spd, the higher spd pet will be helpful) is use. For your prob, get a -spd eq like ironball (special,-40 spd) , shadowpestle (weapon,+55atk -99spd) will be helpful. For fire element, I prefer slow>mess>hotfire>attack>attack(best dmg skill ofcoz). If didnt add so much in wis, can try replace mess with poison.