firstly you should know that when a char enters olympiad all his stats gets back to normal,buffs erased and so on..so the trick with frenzy does not work at all but as you said there is a way,you are right,with a staff of conversion you convert your hp to mp and this lowers your hp before fight so you can use frenzy and can kill the opponent so fast..but be careful of smart mages that may heal you..:P