You speak with Ryne about the plan to use the light of the First.
Requirements
This quest is available if you have completed the quest Seeking the Light.
Starting the Quest
Talk to Ryne in the Crystarium to begin the quest. There will be a cutscene.
Speak with Chai-Nuzz
You can either use the nearby Aethernet Shard to go to the Amaro Launch and talk to the Aspiring Amaro Tamer to go to Eulmore for free, or you can just teleport there.
From the main Eulmore Aetheryte, go east to the quest icon and talk to Chai-Nuzz. There will be a cutscene.
Speak with Zero
Go to the quest icon and talk to Zero.
Speak with the Eulmoran Citizens
Go north to where the orange arrow is pointing in the minimap. You can optionally stand in the glowing circle and talk to Ryne and Zero to discuss the Beehive. Then talk to the Pessimistic Patron to proceed.
Exit the Beehive, then go to the main Eulmore Aetheryte and use it to go to The Mainstay. Go down the stairs and talk to the Solemn Soldier.
Go back up the stairs and use the Aetheryte to go to Nightsoil Pots. Go northwest. You can optionally stand in the glowing circle and talk to Ryne and Zero to discuss the Derelicts. Then go to the quest icon and talk to the Renovating Resident.
Speak with Chai-Nuzz Again
Use the nearby Aethernet Shard to go to the Eulmore Aetheryte Plaza. Go to the quest icon and talk to Chai-Nuzz to proceed. There will be a cutscene.
Speak with Zero Again
Talk to Zero to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Zero to accept the next quest: In Defiance of Fate.