Xenoblade Wiki

The Third Barrier Key is an Important Item in Xenoblade Chronicles X. It must be obtained during Definian Downfall along with the First Barrier Key and the Second Barrier Key to lower a forcefield. It can be found in Cauldros's Ganglion Antropolis, on the eastern ledge of the southeast room.

Definian Downfall map

Map showing the location ("3") of the Third Barrier Key