The Enenra are creatures of smoke and vapor who possess a shapeless form. They are at times created from the souls of slain mortals, and can return to their physical forms.
Tomas Vrbada was kidnapped when he was a child by an obscure cult who intended to sacrifice him to a demon. As he was immolated, he'd changed into an Enenra and killed his kidnappers. After killing the members of the cult, he returned to his mortal form but suffered from amnesia and was unaware of the incident. Some time later he'd joined the Lin Kuei and had taken on the codename Smoke.In Smoke's MK 2011 ending, after defeating Shao Kahn, he regains his memory, and remembers his past life as well as the origin of his powers.
In Mortal Kombat X, the undead Smoke refers to himself as Enenra when addressed by Johnny Cage.