After Miounne sends you to Momodi, she and Papashan ask you to deal with the giants in the Copperbell Mines.
This quest is available if you have completed the quest Call of the Desert, and have reached level 17.
Starting the Quest
To start the quest, talk to Momodi in the Quicksand in Ul'dah. There will be a cutscene.
Speak with Painted Mesa
Talk to Painted Mesa, who is standing nearby, across from Momodi.
Speak with the Stone Torch
Go to Western Thanalan. If you have attuned to the Horizon aetheryte, you can teleport there. If not, you can use an aetheryte in Ul'dah to go to Western Thanalan, and go northwest and across the bridge, then northeast to the area outside of the mines. You can optionally talk to Isildaure and Alianne for a continuation to the story of Dolorous Bear and his companions, whom you saw if you watched the cutscene in Limsa Lominsa after completing Sastasha.
Then talk to Stone Torch to unlock the Copperbell Mines.
Use the Duty Finder or Duty Support to enter The Copperbell Mines. Please see the Copperbell Mines Guide for a walkthrough.
Report to Painted Mesa
Return to the Adventurers' Guild in Ul'dah and talk to Painted Mesa. There will be a glow around him, indicating an instanced battle. Check on him and there will be a cutscene, and then the battle will ensue.
Solo Duty: Into a Copper Hell
First, the Filty Bodyguard will attack. After he takes enough damage, he will summon the Raucous Bodyguard and the Boastful Bodyguard to assist. Focus your attacks on the Raucous Bodyguard, because ranged magic-users have weaker defense. When the Raucous Bodyguard is defeated, focus your attacks on the Filthy Bodyguard again. When he is defeated, focus on the Boastful Bodyguard until the battle ends.
After the battle, there will be a cutscene where the Obnoxious Merchant departs, and your tattooed friend(s) from before will invite you to join their organization, the Scions of the Seventh Dawn.
Speak with Momodi
Go back into the Quicksand and speak with Momodi. There will be a cutscene. If you have been following the tale of Edda (first seen outside of Sastasha), her story continues in this cutscene.
Optional: Unlock the Palace of the Dead
Now that you have completed "Into a Copper Hell", you can unlock the Palace of the Dead, a Deep Dungeon that provides a new type of challenge and a way to earn experience points and other rewards. To unlock it, you can go to Gridania and go to the Carline Canopy, which is south of the Gridania Aetheryte Plaza. Talk to Nojiro Marujiro to accept the quest "The House That Death Built" and complete it to unlock the Palace of the Dead.
Next Main Scenario Quest
After you complete the quest, talk to Momodi to accept the next quest: The Scions of the Seventh Dawn.