Shadow of the Vaal
From Path of Exile Wiki
Once you touch the Ancient Seal in Vaal Ruins Level 2, you will initiate this quest. The world will go dark, and all the NPCs will have something to say to you about this. However, until you complete Deal with the Bandits, you will not have the quest. Once you've done that, talk to Yeena in the Forest Encampment to receive this quest.
To complete this quest, journey through the Waterfall Cave to the Ancient Pyramid and defeat the Vaal Oversoul.
