The robot time dragon was originally a weapon created by Zorgo to steal the time energy from the Doctor's TARDIS. After the Twelfth Doctor and Clara Oswald arrived on Myros, and were identified by two of Zorgo's robots, the dragon appeared and drained the TARDIS's time energy. However, the dragon then began growing in size and spitting vortex energy uncontrollably — one blast of which hit Zorgo. The Doctor and Clara jumped on the dragon and flew away to plug the hole in time and then find his TARDIS. (COMIC: Zorgo the Terrible)
On the 26 September, 2016, the Doctor arrived using the time dragon as a substitute for his TARDIS. He picked up Gertie and Charlie Baker and arrived outside of their house. Due to its connection with the TARDIS, it was able to regurgitate the TARDIS along with its time energy — and thus became an ordinary robot dragon. (COMIC: Super Gran)