In the past, Fang Li had once fought Kanzaki, a Saint.
At the time, Fang Li had been at the limit of the Fourth Level. Thanks to his own abilities and techniques, he had been capable of clashing with powerful Third Level opponents, but facing an existence like a Saint had still been somewhat beyond him.
Even though Fang Li had ultimately won, it had only been because he had desperately endured the period during which he could have been instantly killed. Kanzaki's prolonged use of her Saint's power had gradually accumulated strain on her body, slowing and dulling her movements, and only then had Fang Li found an opportunity to win.
Even then, at the very end, if Fang Li had not comprehended Extreme Death - Seven Nights' ultimate killing technique, based on the same principle as Flash of the God, he likely would not have defeated Kanzaki. It was only later, after he had risen to the Third Level and undergone a tremendous transformation in strength, that Fang Li had gained the confidence to defeat Kanzaki.
This showed just how powerful Saints truly were.
Yet even Kanzaki had only been using a limited amount of a Saint's power.
Combined with her personal rule of never killing anyone, that was why Fang Li had been fortunate enough to claim victory back then.
Otherwise, Fang Li's head might have been cut off by the very first Flash of the God.
Rearguard Water, however, could not only use a Saint's power one hundred percent without any side effects, but also freely wield two hundred percent power, amplified by God's Right Seat ability through the characteristics of the Virgin Mary. On top of that, he could use the water-element magic under his command, employing large-scale spells that ordinary magicians could never cast