A Telkine in Egypt is the 10th chapter of the main quest line, following chapter 9, The Invocation. You will get this quest from Imhotep in Memphis, after he tried to perform the Invocation Ceremony and failed. He quickly conceives a new plan, sending you to the Valley of the Kings near Thebes, where he assumes the Telkine to be, as it is the last site under the protection of the Order of Prometheus still untouched by the Telkine.
Find and defeat Aktaios in the Tomb of Ramses. He will drop the Cuneiform Tablet, a quest item. Bring this tablet to Imhotep, who will now stand near the Gate of Hatshepsut in the Temple of Seti. This will complete the quest and you get some experience, 2 skill points and a quest item, the Scepter of Eternity (which, by the way, is the product of the Eye of Chaos and the Hand of Balance you retrieved earlier). The scepter is required to activate the Portal to Babylon, located in the Temple of Hatshepsut. The next chapter begins, The Sickle of Kronos.
Reward: 12 000 EXP, 2 Skill Points, Scepter of Eternity (Quest Item)