Kill the first wave of enemies until a new enemy called the Butcher arrives. It's only weak point is the ball on its belly. Be careful since it also explodes moments after dying. Kill the last enemies then make your way up. Get inside the building and smash the floor to the lower floor.
Get rid of the vine and before jumping down, destroy the vines across as well. Jump to that room to find a vitality star and some red orb sacs. Jump down and before destroying the crystals, turn around to find the first lost soul of the mission
Apartment Lost Soul, The Order
Smash the next crystals and proceed further until you find a butcher. Defeat it and the next pair of witch and tyrant to proceed inside. Don't forget to grab the health orbs on the walls to restore your HP. Continue until you reach a large hall with angelic vines overhead. Turn around and look to the upper left to find another lost soul.
Climb up the vine and head to the next room. Defeat the next set of enemies here then wait for the door to open. Go downstairs then turn to the right towards the red light. Turn right again and look up behind to find this lost soul.
After getting that soul, backtrack and enter the corridor with green light. Check the corridor to the right to find another soul.
Headquarters Lost Soul, The Order
Continue downstairs left, then right then go past the lamp. Go upstairs and you'll see the copper key behind the counter. Smash the crystals blocking the way and grab the key.
Backtrack to your starting position in this floor, then check the other corridor until you run across a slashed wall and red crystals at The End
. Smash the wall to find a soul inside.
Headquarters Lost Soul 2, The Order
Smash the red crystals and go around the corner. Look up the archway to find another lost soul.
Headquarters Lost Soul 3, The Order
Continue further and you should find a Copper Door. If you followed the instructions, you should have acquired the copper key already. (Secret mission
: Copper – The Power Within)
Backtrack to the stairs where you entered to find the copper key earlier and continue downstairs this time. You should run into a divinity statue so use it as you please. After getting past the statue, turn to the left to find a devil trigger star. Continue to the green door and enter the next room as it opens.
Kill the butcher and the remaining enemies. A new enemy will appear afterward. Unfortunately, this is where the last soul is located and you have to use that fast and dangerous enemy as a stepping stone to reach it. Another problem is that this enemy can't be easily pulled; you need to catch him off guard – and that's the instant that you evade his attack. It may be a bit tricky but you can pull it off with practice.
Headquarters Lost Soul 4, The Order
Just anticipate its attack and counterattack as soon as you recover from evading. Use demon pull or angel lift to instantly close the distance. Keep dealing damage to him until he escapes.