The Order of Prometheus - Act 1 Story Quest
The Order of Prometheus is the sixth main quest in Act 1 of Titan Quest and begins by speaking with Leonidas standing outside of Athens front gate. Much like many of the story quests in this game, you'll begin this quest immediately after completing the previous one, The Battle For Athens. Inside of Athens for the first quest update you'll want to speak with Kyros (pictured above), a man standing next to a wagon just north of the Portal in Athens.
Your quest will update a second time when you enter the Athens Catacombs which are northeast of Athens. Our goal is to venture down to the bottom of the Athens Catacombs where you will need to defeat Alastor, an undead boss monster. The Catacombs themselves are pretty easy, the hardest part will be the stairwells and getting stuck at each doorway. Alastor on the other hand is going to be one of the toughest fights you've had to do up until this point.
Alastor (as with most undead) is immune to Poison, Bleeding and Life Leech damage. He is also heavily resistant to Vitality, Physical and Pierce damage; what this means is that basically 3/4 of the builds in the game will struggle against this boss. If you're a build who primarily uses one of the damage types he is resistant against you have two options. 1 - Use an alternative ability that your build has that deals Elemental Damage or 2 - deal with your craptastic damage and whittle Alastor down.
I'd recommend swapping to any Vitality Resist gear and/or Cold Resist gear for this fight as well if your resists aren't up to par. It'll greatly decrease the amount of damage you're taking from the majority of Alastor's attacks. Below is a list of all the different abilities you should expect Alastor to use:
Auto Attack: He whacks you over the head with his staff. Does Physical damage
Deathchill Aura: Slows Attack Speed if you are in range and deals Cold/Vitality damage
Spectral Bolt: The bolts he shoots out at you deal Cold and Vitality damage
Life Leech & Mana Leech: These abilities work as the name implies
Summon Skeletons: Almost all bosses have an ability like this; Alastor will summon 3 Skeletons to help him in combat up to a total of 6. Every time you defeat all of his pets he will resummon them so it's recommended you always leave at least 1 alive.
Once Alastor has been defeated the door on the opposite end of the room will open and Phaedrus will enter. Speak with Phaedrus to complete this quest and to begin the next one, Under the Labyrinth.