After reaching the city of Ysa, speak with the man waiting behind the bridge and afterwards head to the Court of Summer to meet the king. The entrance can be found at The Font M9(15).
After reaching the throne room, use the Codex of Destiny on the nearby pedestal. A short cinematic will start.
After it ends, you will speak with King Titarion. The choice of dialogue options doesn't have any influence on the further events.
Regardless of what words you use, the King will give you gold, the Fate Potion recipe and a new Twist of Fate - Unwritten One. It permanently increases the amount of gold and experience points that you gain. After speaking with the King, you will have two new missions available: "An Old Friend" and "The Great General". You can complete them in any order you like. Their description can be found in other parts of the guide, related with further lands of Amalur.