Pressure

Changing his own voice could avoid a great deal of trouble. The mask Vizet wore had a similar effect, allowing him to alter his voice;

He had even added the Soul Guiding Box, using the Soul Fragment Tom Riddle had left behind to further change his aura as well.

Professor Snape had probably appeared with a hoarse voice for much the same reason;

But the "this is not there" he had mentioned clearly meant that the Duelling Stage was not Hogwarts. It was practically an open hint at his identity.

Professor Snape openly hinting at his identity did not mean Vizet could afford to be careless. On the contrary, it meant he had to go all out if he wanted any chance of claiming the final victory.

Seeing Professor Snape closing in on him at high speed, Vizet simultaneously pulled back, twisting his wrist to draw an extremely short "1."

The invisible shield condensed by the Shield Charm had only just taken shape when Professor Snape's Cutting Curse appeared in front of him. The sharp blade of light slammed into the invisible shield, bursting out with a dull, heavy boom.

Vizet twisted his wrist again, waving his Wand to trace an arc. The broken stones on the ground twisted and took form, becoming three rock spears angled from viciously tricky positions as they stabbed at Professor Snape all at once.

Professor Snape stepped forward, seeming to dodge one of the rock spears by a hair's breadth, then, as if swinging a longsword, flung out two Cutting Curses and severed all three rock spears at the same time.

The severed rock spears did not fall to the ground. Instead, they stabbed straight at Vizet, only completing their transformation midflight and turning into six arrows.

"Whirlwind Sudden Roll!" Vizet shouted the spell