* The Suicide Virus. Yoshimatsu's wonderland gone horribly wrong. Nami can freeze people's blood. Okada's shinigami. The owl. You know what, it's just easier to say everything is nightmare fuel.
* Yura's power is to create bubbles of high-compressed air that explode when he wants them to. He uses it to kill everyone in his way at the slightest provocation.
* Yuta in Chapter 5 creates a barrier with enough oxygen for 4 hours. Nothing seen outside the barrier moves, with the sun and clouds staying in place. It's an isolated world in itself and you're at his mercy.