When Julia is a support character, defeat an enemy that normally is capable of killing itself - such as the Bomber Heads in Mt. Gundor that can explode to hurt you. Once defeated, before it disappears, activate Julia's ability. From here, you can do this twice more (provided Julia has enough energy), though you have to let the enemy in question kill itself since from this point onward you cannot directly deal damage to the monster. Each time the monster dies, it will drop money and perhaps items, allowing you to duplicate the rewards you earn.