To find the ledge with this loot chest, you need to progress into the story enough to open up the path that leads to Crisis Scar. Once you do, get onto this path and as soon as you enter, look up and to the left to see a ledge. To get to this, make your way to the far end, where you'll use a jump pad to get to the elevated area. Up here is another jump pad that you can use to reach that ledge, where you can open the loot chest to finish the challenge.
This is a one-time challenge. During the Let's Build a Robot Army story mission, you will have to take a train from Triton Flats to Titan Industrial Facility. When you get to the train station in Triton Flats, you will have to call for the train and while you're waiting, three Shugguraths will show up. You'll have to kill these within one minute, so you'll have to likely ignore the Rathyds the Shugguraths spit out.
Leap of Faith
You will need to make your way to the Darksiders tower, which you happen to traverse during the story mission, A New Direction . Near the top will be a jump pad that launches you onto a balcony and there will be another balcony on the other side, which is where you want to be. Later on, after completing the next story mission, you will be able to get a optional mission up here called No Such Thing as a Free Launch .
Once you get onto the eastern balcony, look down below to see a octagonal-shaped building with a makeshift covering on it. You need to boost jump over to this covering and perform a butt slam from high in the air, which will destroy it and reveal a loot chest. You'll complete the challenge as soon as you destroy the covering.
You will need to find four ECHO recordings that give some insight about Wilhelm. Note that they are all located next to a crashed rocket site, so be on the lookout for those when trying to locate the ECHOs.
- In the southwest corner of the map will be a vehicle spawning station, but you want to go to the area just north of it. You should find a crash site there with the ECHO.
- When you first enter Triton Flats from Concordia, you can see a jump of sorts over the magma river northwest of you. Just west of the jump will be a crash site with the ECHO.
- In the northern part of the map, you should see what looks like a road cutting through the map. Just north of the Air Dome Generator that's along this road will be a crash site with the ECHO.
- Follow that road from the previous one to the west/northwest. Right before the gap in it, which leads to a train station, will be the crash site with the ECHO.