Growing more concerned for Biggs by the moment, Wedge asks you to ask others in the tower for assistance.
This quest is available if you have completed the quest Monumental Hopes.
Starting the Quest
Talk to Wedge in Monument Tower in the southwestern part of Coerthas Central Highlands to begin the quest.
Speak with Ignace
Go up the spiral staircase in the tower until you find Ignace. Talk to him.
Head to Daniffen Pass
Exit the tower and go northeast to where the orange arrow is pointing in the minimap. You will find Yda, along with Y'shtola, There will be a glow around her, indicating an instanced battle. Check on her and there will be a cutscene, and then the battle will ensue.
Solo Duty: Notorious Biggs
Defeat the Imperial Sagittarii and Imperial Laquearii. Ignore the Imperial Decurion.
When more enemies appear, quickly kill the Magitek Vanguards, followed by the Magitek Vanguard H-1s, since they target Biggs, and you will fail the duty if Biggs dies. Defeat any remaining Sagittarii and Laquearii, but if more Magitek appear, kill them first.
If the Decurion is still alive after that, defeat him to complete the duty. There will be a cutscene.
Report to Wedge
Go southwest to Monument Tower and go inside. Talk to Wedge to complete the quest. There will be a cutscene.
Next Main Scenario Quest
After you complete the quest, talk to Cid to accept the next quest: Come-Into-My-Castrum.