The Sickle of Kronos - Act 2 Story Quest
The Sickle of Kronos is the 4th main quest in Act 2 and begins by speaking with Imhotep in the town of Thebes (pictured above). Go through the door behind Imhotep and follow the linear path until you find the Temple of Hatshepsut. Our destination is the bottom of the temple (quite a long run) which is where you will find a Sand Wraithlord - Nightmare of the Desert (pictured below).
A tip for most of you, outside of the Temple of Hatshepsut you'll find a couple of Dark Obelisks outside of the temple. These enemies give you a disproportionate amount of EXP in comparison to other enemies in the area and are definitely worth defeating. Often this location is mentioned in guides asking where the best location to grind EXP is in Titan Quest - that's how good they are.
Sand Wraithlord - Nightmare of the Desert is the final boss in Act 2 and is very annoying but not all that difficult. He deals primarily Fire damage and the biggest issue of the entire fight will be Skill Disruption. Thankfully his damage is so low that you can pretty easily tank him, however, your damage will be so low you can barely kill him too if you lack Skill Disruption Resistance.
Below is a list of all the abilities you should expect the Sand Wraithlord to use:
Fire Strike: He deals fire damage with his regular attacks
Speed Aura: Boosts his movement speed as well as his minions
Sand Storm: Much like the previous Telkine he will do a large wave of sand around himself, hitting everyone in melee
Sandblast: Chucks a ball of sand at you that deals Fire and Physical damage
Summon Sandwraiths: He can summon up to a total of 4 Sandwraiths which will help him in combat. They are weak and be easily dispatched
With the Sand Wraithlord defeated go into the adjacent room and place the staff into the pedestal to open up the portal to Babylon. This quest will automatically complete when you click on the portal and you'll begin the next one, The Sickle of Kronos (Act 3).