Gravis was trapped in a perilous situation. He had to harden his body to survive these shockwaves, but with this strengthened body, it would become too heavy to lift. If he wanted to escape the area, he would need to lighten his body, but then, a single shockwave would reduce him to dust. But if he strengthened it, he would fall! After all, there was no gap in the wall to keep him steady.
Gravis quickly realized that there was only one way to survive. If he remained in the air like this, he would die. So, Gravis decided to shoot towards the ground.
BANG!
Another shockwave arrived, but with Gravis' previous experience, he was able to protect himself better. Instead of being hit across his whole body, he angled himself so that his feet were pointing at the shockwave.