Near the Teleport Waypoint south of Old Vanarana, you'll find an Eremite camp with an Energy Extraction Device that can be diffused with the help of Control Keys. Reference the image below to find the exact location of the Challenge. Since the area is swarming with enemy Eremites, make sure to bring a battle-ready team.
Once you get there, you'll find a mechanism called an Energy Extraction Device. Approach it to begin a Challenge where you must find three Control Keys to deactivate the Device.
How to Look for a way to control the extractor in Genshin Impact
In this part, you need to find the three missing Control Keys in order to shut down the Energy Extraction Device. You can obtain them in any order.
First Control Key location
Head to the smaller building in front of the Energy Extraction Device and interact with the switch to open the gate, allowing you to enter the room. Once inside, approach the first Control Key to obtain it. A Common Chest will also appear to the left of the Control Key—don't forget to loot it!
Second Control Key location
Head toward the larger building behind the Energy Extraction Device. You'll notice that part of the building is cracked (pictured above). Enter the crack to find the second Control Key, which you need to approach to get.
Third Control Key location
In the same room where you found the second Control Key, look up to find a hole in the ceiling. Enter the hole to find the third Control Key. After approaching it, the gates in the room will unlock, allowing you to exit.
How to guard the extractor until it shuts down in Genshin Impact
After obtaining all three Control Keys, interact with the Energy Extractor Device at the top of the building to begin a battle segment. A circular gauge will appear above it. Your goal is to stand beside the Device until the gauge above it becomes full. If you're too far away or if there are enemy disruptions, the gauge will stop filling up, so make sure to defeat all the enemies that spawn and stand close to the Device afterward. Once the gauge is all filled up, the Energy Extraction Device will turn off, rewarding you with an Exquisite Chest.
Check out our guide on How to solve the Energy Extraction Device Challenge in Gandha Hill in Genshin Impact to complete a similar Challenge in another part of Sumeru.