Wiki - Journey to the Underworld
Part 1 - Underworld Minions
Philoctetes can be found outside the Arena in Luna. The first part of the quest is simple. Would be heroes must travel to Trammel Khaldun and prove they are heroes by slaying a number of Underworld Minions.
Defeat all the enemies that Philoctetes asked you to and return to him to get the second part of the quest.
Part 2 - Underworld Masters
Go back to the dungeon and find, and defeat, the Underworld's Masters: Phobos, Thanatos, and Hypnos. On each you'll find an object. Philoctetes requires both the slaying and the gathering of these objects to prove the adventurer is a hero. Return to him for your random reward. Rewards are on display in the display area on the world omniporter.