In each stage, there is a certain chance to encounter the Monument of Aeterna (guaranteed to appear at Timemark 7 and above). Interacting with it will allow you to enter the special map, Ruins of Aeterna. Completing challenges and defeating monsters within the Ruins of Aeterna will grant you rewards. Most importantly, you will obtain a fragment of The City of Aeterna – the Mark of the Ruins.
When you have collected enough Mark of the Ruins, socket them onto the Aeterna Map. Once the Aeterna Map is complete, you can enter The City of Aeterna through the Monument of Aeterna or Kandel. Defeating monsters in The City of Aeterna will grant you Energy, and collecting a certain amount of Energy will reward you with Kindling. Offering Kindling to the Sacrificial Bonfire will grant you generous rewards. When the Sacrificial Bonfire progress is full, you can challenge the boss of The City of Aeterna. The more Bonfires you have, the better the boss rewards will be.
In the new season, join the massive Season Talent Tree, where you can unlock Talent Nodes to gain a completely different season experience, while obtaining numerous battle buffs and additional map rewards. Expand the territory of Aeterna and ultimately unlock the Infinite City of Aeterna.
After unlocking the Infinite City of Aeterna, each time a hunter clears the Aeterna stage (with an average level of 85 or above), the city will advance one step further in the eternal dimension. The city will become more dangerous, but the rewards will also become increasingly abundant. There is no upper limit to the level of the Aeterna city.
Torchlight Infinite Flame Elementium