The Doombringer was a Harrower-class dreadnought equipped with the Silencer, a superlaser capable of destroying an entire fleet. During the Cold War it was Moff Pyron's flagship and became part of Darth Nox's fleet.
The Silencer was attached to the front of the Dreadnaught so that it could be fired up quickly.
The Doombringer fought for the Sith Empire in the Cold War under the command of Moff Valion Pyron and was chosen to be the first Imperial Dreadnaught to test the Silencer, a powerful superlaser built by the Empire which was able to wipe out an entire fleet. The Sith Lord Kallig visited the Doombringer to see the superlaser's power itself, hoping that the demonstration could help him gather allies in the Empire. After the Silencer destroyed an entire Republic Fleet, Kallig ordered that all the Dreadnaughts under command of his allies to be equipped with one Silencer Superlaser.