Wraith

Wraiths, also known as Spectres, are a species of undead creatures originating from the Netherrealm. They are created when damned souls strike deals with powerful sorcerers or the like. They are granted an escape from the Netherrealm and powerful hellish abilities, in return for loyal servitude. They are far more powerful than revenants, however the amount of power needed to create them is also much more than what is needed to create a revenant.