Getting the dive bomb is key. You must activated the elevator before skipping it or you just screw yourself. Activate the 2 back turrets to help you clear the first bunch of thralls. Not the first 2 on the side you come from because they might make getting 5 before the 2nd part of the elevator nearly impossible. The key to the dive bomb jumps is to be as close to the collision as possible before using it. The 2nd dive bomb jump(at 3:40) in the ruins has to be done in the the lower half of the collision you clip through or you won’t gain enough height. Beat the boss then use the same jump in the ruins again(at 3:28) to jump over to the other side. When you jump to fight Arc make sure you fall into the checkpoint area just to be safe. You have to clear the ruins too to see whether you need to jump to Arc or Vyn. Use the turrets to make it easier. You can do this with several people. Just watch the life count and use the checkpoints to spawn into the boss fights or all be Benny.
The only trouble I’ve had with the Sentinel was one time in a public mission, we played through the level like normal, but the second jumper never spawned after beating the miniboss, and we couldn’t go to the next area, because the jumper was the only way up. xD
We just did a suicide pact.