The Warlocks of Demigest were a group of humans who were transformed by primal universal forces present on the planet Demigest. The transformation gave the Warlocks powers, such as the ability to change their size, enhanced speed and strength.
Sabbath captured two of the Warlocks and attempted to use them to control the infinity forces on Selonart. Sabbath's plan failed, and the Warlocks imprisoned him on Demigest. The Eighth Doctor travelled to Demigest and tricked the Warlocks into opening a box containing the infinity forces, which forced them to change once more, eventually destroying them. (PROSE: The Infinity Race)