Grey's figure flashed through the darkness, he was moving at a frightening speed, but his pace drastically reduced within a second. He had gone very deep into the miasma, and it had started attacking him. Grey currently isn't able to stay there for too long, even the slightest contact with it is enough to kill some Peak Sovereigns, yet Grey was fully engulfed in it. His eyes turned black, as the cracks appeared in his body in a matter of seconds.
His light element kicked in instantly, trying to heal him as fast as it could, but his body was deteriorating at a faster rate. Even if a Light Elementalist at the Peak of the Sovereign Plane was caught in this place, they wouldn't be able to keep up with the speed at which the miasma was corroding their body.
The reason Grey was still alive was due to his terrifying physical body.