The Black Smoke Charm (Oscuro) is a charm used to create a thick black smokescreen.
The Black Smoke Charm generates an explosion of black smoke, exactly like a smokescreen, from the tip of the wand. The smokescreen is used to obscure the user from view, allowing for a quick escape. It can be seen as a spell with a similar effect to the Peruvian Instant Darkness Powder, with the one difference being its ability to be navigated through with light-casting spells. It is, thus, far more inefficient than the magical item, but easier to use should one be unable to acquire such powder from Peru.
The incantation comes from a Spanish word, meaning "dark".
- Peruvian Instant Darkness Powder on Harry Potter Wiki