Use the Sensor Backpack to find an energy fluctuation around Loot Lake is a Week 8 Resistance challenge in Fortnite Chapter 3 Season 2.
If you want to complete this Fortnite challenge, you must first ensure you’ve finished all of the Resistance challenges released between Week 1 to 8. After doing so, you must work through the Week 8 Resistance challenges, which include talking to Mancake, Bao Bros and Lil Whip, along with collecting the Signal Jammers.
Completing this challenge will reward you with 23k XP, which will help you unlock more skins from the current Battle Pass.