Shoki (InuYasha)

Shōki: (miasma-energy) Also translated as just “miasma.” Rather than being the "magical" energy created by youkai, shouki is the fumes/gas that can be created by youkai, as well as potions, powders, and the like.

Naraku oftent uses this to blind his enemy and escape.he can inject the shoki into someones body by using his tentacles (wich he does by both kagura and kikyo)

also sango and the other taijiya (youkai exterminators) use shoki to exterminate weak youkai.