Devolver

The Devolver was a weapon created by the Wraxians using technology left behind by the Kotturuh.

The Devolver was housed in the Eye of Wrax. The Wraxians used it to eliminate rival civilisations by reverting them through generations of ancestry. When the Doctor and the Dalek Time Squad came to Wrax, the Wraxians planned to use it against the Daleks. With the Daleks invading to stop them, the Doctor negotiated with the Wraxian President for them to dismantle the Devolver in return for the Daleks’ withdrawal. The President agreed however the Dalek Executioner secretly returned to planet and used the Devolver to exterminate the Wraxians before it could be dismantled. (AUDIO: The Enemy of My Enemy)

At a later point the Master found the Devolver abandoned and miniaturized it into a more portable version. He used it during his heist on the Repository, killing many in his way with the Devolver.  (AUDIO: Master Thief)