Shoki (InuYasha)

In the anime and manga series, InuYasha, shōki (沼気), which is known as miasma in the English version, is a poisonous gas employed by Naraku. It isn't so much an attack as it is a boundary. The shōki is a standing field of purplish gas, toxic in nature, which surrounds any place he wishes to secure. The gas itself has 'slow kill' properties, gradually poisoning anyone entering it within a matter of minutes.

It can also take the more deadly form of a liquid, which melts almost anything it comes in contact with. But it doesn't take the form of a liquid until later into the series, suggesting that it requires more effort for Naraku to make the liquid form.