Assassin's Creed Origins: Curse of the Pharaohs - Sting in the Tale Trophy / Achievement Guide (AC Origins DLC)
For the Sting in the Tale trophy/achievement, you need to "Complete the 5 Serqet locations" in the Curse of the Pharaohs DLC. Four of the locations can be found in the afterlife zones, and the other one can be found in the main zone the DLC takes place in.
You need to complete the fort location for the real world Serqet location, and for the afterlife ones you need to defeat a lvl 58 Scorpion which is always lvl 58.
Completing the objectives at all 5 of the locations will reward you with the "Sting in the Tale" trophy/achievement and the legendary outfit "Serqet Carapace".
All Serqet Locations
Spring of Serqet - Waset Desert
Serqet's Garden - Aten (Afterlife Zone)
Serqet's Altar - Aaru (Afterlife Zone)
Serqet's Chamber - Heb Sed (Afterlife Zone)
Hall's of Serqet - Duat (Afterlife Zone)