This guy is located in the Ancient's Maze. Titan is guarding the crystal that will give you the final jobs available in the game, so it's absolutely vital you defeat him. Thankfully, he's somewhat of a pushover at this point in the game. Though he attacks twice per round with fairly devastating physical attacks, that's about as far as the threat he poses goes. He has a high defense that will give him some resilience in the battle, but it should only take four rounds max to defeat this foe. Try casting high level magic on him if you can, and stick to physical attacks as well, which will have moderate success on the enemy.