WILD ROCK'S attack was a huge sword slash. The rink that had returned to normal after the fight between Supreme King and Lovelee immediately sustained a new damage. That slash was so powerful that a deep dent appeared on the part of the rink where the slash travelled.
But despite the power that that sword slash showed, Razor just continued to stand there. The audience thought that it's either he didn't think much of the opponent's attack or he was frozen scared by it.
The force of the attack was so strong that it produced rubbles from the rink. These rubbles made some kind of smoke screen. That's why no one knew if the attack hit Razor or not.
But before the audience found the answer to that, a black stream flashed through the rubble of smoke. Most people wouldn't have seen that. But for Wild Rock, who was on the rink and close the smoke, he could clearly see this 'black stream'. It was moving too fast that he could even hear the 'swish' sound it was making.
