Circle of Transcendence

The  was built by Anubis with the help of his key by Horus' request. Its purpose was to allow all Osirans to escape to a higher, four-dimensional universe. By Horus' command, Anubis was left as the Circle's guardian until all Osiran technology is purged from the universe. The millennia that the purge required caused a degradation in the polar quantum articulations. If Anubis used the Circle to finally ascend himself, the universe would have been destroyed. The Tenth Doctor and Dorothy Bell managed to persuade Anubis to wait until the Doctor helped him to fix the Circle. (COMIC: Sins of the Father)