Deathsmiths of Goth

The Deathsmiths of Goth, expert weapons designers, were once more feared than the Daleks.

On their home planet of Goth, they created a superweapon known as the Apocalypse Device, but this creation went out of control and began killing them. To contain this weapon, the Deathsmiths destroyed all spaceships on the planet, leaving the Apocalypse Device stranded on Goth among the ruins. (COMIC: Black Legacy)

The Dalek Emperor "let loose" the Deathsmiths of Goth against the Time Lords during the Last Great Time War. (PROSE: A Brief History of Time Lords) They foresaw the "final event" of Gallifrey's destruction by the Doctor using the Moment. (PROSE: Doctor Who and the Time War)

Weapons
The Deathsmiths created the Cellular Disruptor, Implosion Grenades, Brain Wave Scrambler, a Thermic Cutter and the superweapon Apocalypse Device. (COMIC: Black Legacy)

Behind the scenes

 * According to Doctor Who: Monsters and Villains, a non-narrative source, in the Fifth Calendar Year of 111222/9967, to alleviate the Earth's terrible debts, Brazil and its five million occupants were sold to the Deathsmiths of Goth and experimented on in bizarre and terrible ways.