Black hole converter
From Tardis Wiki, the free Doctor Who reference
A black hole converter was a device which the Master placed on each of his warships. They were intended to destroy other planets once the Time Lord Empire launched its war against the Universe. When he lost control of Earth, he told the Tenth Doctor he would rather destroy it, but the Doctor talked him out of it. When time was reversed, the warships and black hole converter faded away. (DW: Last of the Time Lords)
