Gas

Gas is a long-range Emitter power held by the young Villain Mustard. Rather than striking a target, it converts the surrounding terrain into a hazard: a slow, poisonous fog that puts people down and reports their movements back to the person who made it.

Its ceiling is high and its floor is low. Handled well it can neutralize dozens of opponents at once, but a single piece of common equipment renders it inert.

The user's body vents a toxic purple vapor. Anyone who inhales it directly drops unconscious almost immediately, and nothing wakes them until the poison itself receives treatment. Mustard can produce enough of it to swallow the Beast's Forest whole, arranging the cloud as a typhoon with himself at its center.

Density governs everything. Potency peaks near the source and thins toward the outer edges, and moving through the thick of it is comparable to navigating heavy fog. Fluctuations in the vapor betray the presence and travel speed of anyone inside, turning the whole cloud into a tracking field.

The drawbacks are numerous. Any breathing filter defeats the poison outright, and thin patches barely register. The vapor cannot be steered past its natural flow, which leaves the user badly equipped for a direct fight. Itsuka Kendo demonstrated that a strong enough gust scatters it and wrecks detection along with it. The range, while wide, still ends not far beyond the forest. Most critically, the poison ignores its own maker: knock the user unconscious and the entire cloud dissipates at once.

Mustard is the sole known holder. He builds his approach around what the cloud does well, sealing off escape routes and boxing in opponents while keeping well clear of them, serving as an ambusher rather than a front-line fighter and reading the vapor's flow so nobody reaches him unseen. Since the poison affects him too, a mask stays on his face throughout, and he carries a handgun to handle anyone whose own breathing apparatus makes them immune. Tetsutetsu Tetsutetsu eventually ends the fight by knocking him out, which clears the forest instantly.

Two comparable powers exist. Somnambulist also induces sleep but lacks toxic properties, spares its user entirely, and cannot force anyone into deep unconsciousness. Poison Gas is nearer still, generating a harmful cloud from the body that can affect the person emitting it.