Smoke

Smoke, also known as Smoke Bomb and Dustb, is a recurring ability in the Final Fantasy series. It is a type of Ninjutsu magic, and is sometimes an item. When used it allows the party to instantly escape from battle.

Final Fantasy IV
Smoke, known as Smokebomb in the J2e translation, is a Ninjutsu spell usable by Edge, which he learns at level 33 in all versions. It costs 5 MP in the Nintendo DS version and 10 MP in all other versions. In the GBA version, a glitch may cause the Smoke particle effect to not appear on all characters, though the ability has succeeded.

Final Fantasy IV -Interlude-
Smoke returns as a Ninjutsu spell in the sequel of Final Fantasy IV and Edge already known the spell. It allows the party to escape from random battles at the cost of 10 MP.

Final Fantasy V
Ninjas have !Smoke, also known as Dustb, which is a Level One command ability that instantly has the party escape from battle. It requires 10 AP to learn.

Final Fantasy
The Smoke Bomb is not a command, but an item.

Final Fantasy VII
The Smoke Bomb returns as an item.

Final Fantasy Dimensions
The Ninja can use Smoke Bomb at Job Level 13.

Etymology
The ability's existence is based on the common depiction of ninjas in fiction, where they often use explosive powders to create bursts of smoke to distract and blind their enemies, allowing them to escape.