Lost Souls: 6
Doors: Argent, Copper
Keys: Argent, Copper
Keep following Kat until you enter Limbo. There's a lost soul here but it can be difficult to give directions so kindly refer to the video below to reach it.
Keep jumping on the crates until you reach the upper platform where you'll fight a hell knight. Defeat it and the next set of enemies to open up the path. Before leaving, jump on the container van to the right to reach the copper key inside. Check the video below.
After getting the copper key, don't leave yet. Look at the edge of the platform then jump and immediately pull yourself using angel lift to reach the other platform containing a lost soul.
Continue to reach the divinity statue. Climb up the stack of crates and jump to the next stack. Continue climbing up then jump to the upper ledge to reach the copper door there.
Once done, return to ground level and continue forth. You'll encounter a demon shard ahead so shoot it down then climb the next layer of container vans until you reach the next area. Take out the shielded Pathos then pull yourself to the next walkway. You'll find a lost soul there.
Make your way to the platform where there the glowing yellow veins are then defeat the Frost and Hell Knights. Before heading inside the mixing room, go to the other end of the platform and free the lost soul there. Backtrack to the entrance then look up. You should find another lost soul there. Jump on the platform to the right then grab the edge of the ledge to reach the lost soul.
Now, you can also reach the Argent Key located in the same area. Refer to the video below for more details.
After getting the collectibles available in this area. Enter the hallway and engage the enemies in the next area. The last wave will consist of three demonic shards so shoot them quickly before you get hit. Continue forth and turn right to the first hallway. Destroy the demonic shard there and follow it to the end and destroy the web using Osiris.
Backtrack a bit to the last intersection then turn left. Keep following the path until you find a destructible door to the left which leads to an argent door. If you acquired the argent key earlier, you should be able to open this secret door.
Argent – Displaced Skirmish
From the secret door, follow the path then use the divinity statue along the way. Once you've reached the mixing room, avoid the liquid spills and take out the enemies. Meet up with Kat to complete the mission.