The Ravager was a Sith artifact created by the Emperor of the resurgent Sith Empire that ripped information from its victims' minds, driving them insane and slowly killing them in the process. The Emperor locked it away in the Dark Temple on Dromund Kaas not long after its creation.
In 3643 BBY, during the Cold War, Darth Baras sent his apprentice into the Dark Temple to retrieve the Ravager. Baras' intent for the device was to break a captive SIS agent, Grik Sonosan, who was proving resistant to brutal interrogation. The apprentice assembled all the pieces of the Ravager and brought it back to Baras. He then placed it atop Sonosan's forehead, and it activated, finally breaking the agent and forced him to reveal the threat to Baras' network of spies. But before Baras could obtain all the information he desired, the Ravager liquefied Sonosan's mind, killing him.