Harry hurried forward, bringing his wand to bear and his will. "Aguamenti Maximus, "Aguamenti Totallus!" he hurled the spell combination forward, splitting it, like he had been taught as an Auror, and flinging all of his might against this snake of fire. It looked and felt almost like Nagini, and he loathed that thing.
Magius swallowed as the spells went pear shaped and he realized he had no choice. he switched gears mid-spell, hoping the last of the magic he flung at the wind wall spell would hold it for a few moments longer, even as he brought his will to bear on one of the most powerful spells he wielded now.
He could not cast it's more powerful cousin, but "Dispel Magic" still flowed form his mind and body as he shouted it aloud, carrying power and command, as he hurled it at the center of the problem, the book, the serpent, and the contorted flame. There was a gathering of power, and a rage of flame rising, and then a silver took root in the middle of it, a silvery light that ate the flame, and rolled toward the snake, burning with the power of the all devouring spell. It rolled over the edges of the snake and up it, leaving nothing but air as it ate the magic entire. And Magius felt the battering of the thing's magic against his will, his magic, and pressed, teeth gritted. He would not fail.