Which figure of speech is used in this text?
There has been an incident on Praxis.
—Brigadier Kerla, after Praxis is destroyed in Star Trek VI: The Undiscovered Country

 - hyperbole
 - understatement
The text uses understatement, which involves deliberately representing something as less serious or important than it really is.
An incident on Praxis is an understatement, since Praxis has been destroyed.