As this red miasma covered Seth, he first felt like he had been dropped in the sea, as his surroundings resisted his movements like he was deep in water, and then before he knew it, these feelings changed to him now beginning to feel like he was in a pool of glue, as his movements quickly became restricted.
The procedural but near-instantaneous restriction wasn't the only effect the red miasma had on Seth as the second the thick red gas had touched him, Seth's body was hit with nerve wrecking pain as his skin began melting off.
The minute Zuroc had detonated his arm, Seth knew he was in trouble and could not let Zuroc recover or stabilize himself, so even as the red miasma covered and restricted him, he had kept his eyes fluttering as much as he could, tracking Zuroc's staggering movement's and when he felt the time was right he let loose.