The Technomancers were an advanced race of mages from the early days of the galaxy who combined magic and technology. Based on the planet Aldriss, the Time Lords allied with them during the Last Great Time War; Shadovar told Jarad that trying to explain his people's technology to him was like the Time Lords trying to explain their technology to microscopic bacteria.
They worshiped and drew their power from the Horned Ones. Part of their technology/magic included using chalk circles to keep prisoners, and being able to prevent messages from leaving their world. They could also cast protection spells to keep their world from detection. (AUDIO: Legion of the Lost)