Erasfol was a Time Lord during the War in Heaven.
Erasfol was part of Xenaria's expedition to break the time loop surrounding Planet 5 about 12 million BC, so the Fendahl could be released and used against the Enemy. Like all members of the expedition, Erasfol had been changed into a Elder Thing as camouflage during the time period. Just before Investigator OneO left the Antarctic base, Erasfol - along with Machtien, Urtshi, Ventak, and Neinthe-, under Xenaria's direct order, fired on the Investigator, until he was almost killed and teleported away.(PROSE: The Taking of Planet 5)