At the end of the previous chapter of the main quest, Under Wusao Mountain, the telkine Ormenos freed the last titan, Typhon. Defeating Ormenos in Typhon's prison ended the chapter and freed the way to the portal in the room. It leads to Olympus, home of the gods, and the epic boss battle against Typhon (click his name for a battle guide).
This is the end of Titan Quest. If you own the first expansion, Immortal Throne (it is included in the Anniversary Edition), a portal will lead from the boss fight arena to Rhodes, the first town of Act IV. Talk to Tiresias right after passing through the portal to start the first chapter of Act IV of the main story, A Mysterious Message.
- Normal: 30k Experience
- Loot from Typhon (repeatable for item farming, although defeating a special monster like Typhon for the first time grants bonus loot from that particular monster)