Deca

The Deca was a group of ten members of the Timelord Council. All of the group's members were among the youngest in the council, and all were friends of Theta Sigma. The Deca was opposed to the isolationist policies which were endemic to the higher members of the council at the time.

The organisation began while founder members Koschei, Magnus and Theta Sigma were students at the Academy, and grew in size over the subsequent centuries. It was notable for including members from across the breadth of the council's Chapters, which were typically in competition with one another.

The Deca's members were accused of high treason and plotting rebellion, and a Commander was sent to arrest them under orders of the Castellan, while they met at Koschei's house. It was this incident which led to the presumed downfall of the group, with Koschei fleeing Gallifrey, Theta being exiled to Earth, and many of the others being arrested.