Salvation's Edge Raid -Scenic Route (Substratum Encounter) Master Challenge

Our teammate had a very easy way to go about this, and it all tied into what ads spawn in the room you go into first with your team.
Hobgoblins means for that team, you push forward, and eventually, you'll deal with the Overload Champion.
In contrast, Psion spawn means that... Well, you stay in that first room with your team and keep killing Hydras (should only be 2) until the Champ goes down, spawning the Tormentor.
After Tormentor, it's rinse and repeat. It is important to remember where the first Overload was killed as that plate will be active... But more importantly, Hydras will still need to be killed to progress for the other team to get the second tormentor.
After a couple of attempts, we got it down pretty quick.