Sacred oaths and blessed weapons are the usual weapons of a priest in the DL. Cristo turns that stereotype on it's head, winning fights with a dizzying array of status magic and taking oceans of punishment. Disabling this hellish monster is certainly a worthy task for the devout. Fizzle ruins Zapdos's magical attacks, Dazzle ruins his accuracy, and Whack kills the bird in a single shot. If that isn't enough, Cristo has more than enough MP to outlast the worst of what Zapdos can do. Of course, any hope the bird has of winning requires outspeeding Cristo, no easy task against the fleet footed hero!
