The Cataclysm was a major event in the history of Atreia. In an attempt to end the Millennium War, Lord Israphel called for peace with the Dragon Lords , making an offer to lower the Aetheric Field . However, this would leave the Tower of Eternity vulnerable and was hotly debated among the Empyrean Lords, who were divided on the issue.
One group, led by Lady Ariel, supported Israphel’s call for peace and argued that lowering the Field would be a gesture of good faith and could open the door for discourse and possibly an end to the war. Lord Azphel had a different view. He was of the opinion that lowering the Aetheric Field was foolish and showed weakness on their part--weakness that the Dragon Lords would surely plan to use to their own advantage. In the end, the Aetheric Field was lowered and the Dragon Lords arrived. As the conversation began, an unknown assassin attempted to take the life of a Dragon Lord Beritra.
In reality however the Archdaeva and those who loyal to him, saw a chance to destroy the Balaur threat once and for all. A fierce battle started with the Archdaeva giving orders of a charge against Fregion and the balaur accompanying him. The Tower of Eternity was shattered, breaking Atreia apart with it. It is now as it was then. This tragic event is known today as the Cataclysm.
In Aion 5.0, it was revealed the two Tower halves were simply frozen in time by Siel. She succeeded to stop the collapse, but with a price and it was only temporary. Aetria is facing complete destruction once again, as Siel's aetheric field is starting to weaken.