Lost Souls: 9
Doors: x2 Copper
Keys: 1 argent, 1 copper
After the scene, head to the large hall. Destroy the sacs on the walls to get red orbs then continue upstairs. There's a Copper key in the room at the end of the hallway to the right and more spiders/ orb sacs in the adjacent room across. Ignore the hallway on the ground; take the stairs to the left and follow the corridor past the divinity statue that leads to another hall.
After the scene, dispatch the first wave of enemies then take out the Death Knight. Approach Sparda's painting to get a new weapon called the Arbiter.
Head to the next hallway to find a Lost Soul. The wall will be moved back so to reach that soul, you have to double jump and air dash to reach it. Jump to the hole below and find another lost soul on the wall to the left after landing.
Follow the path until you reach the main hall before. Kill the enemies then go upstairs to find a red, slashed door. Smash it open using the Arbiter. Before moving forth, turn around and look up the doorway to find another lost soul.
Continue to the next room and kill the Death Knights. After the scene, you'll be taken into an ethereal world. Jump across the floating platforms until you unlock the Ophion Demon Pull ability.
Pull the marked platform so you can jump across then continue forth. You'll encounter a few basic enemies ahead so you can test your Ophion whip in combat. Continue forth until you reach the base of the chain holding the statue. Smash it with the Arbiter to return back.
Jump down the hole on the floor then open the Copper Door for another secret mission. The secret mission is fairly simple so just kill all the enemies as fast as you can within the time limit.
Copper Door – Simple Eradication
After the mission, continue to the next hallway then pull the platform for you to cross. Before crossing, turn around and look above the doorway to find another lost soul.
Jump on the platform and continue pulling until you reach a door. Smash it open with Arbiter then head to the next hallway to find an apparition. Continue back to the main hall until it gets destroyed and you have to defeat a new flying enemy called the Shielded Bathios. You can use your demon whip to pull their shields away and render them to become ordinary Bathioses. After defeating them, continue to the large door where the apparition headed.
Smash the door open then use the divinity statue inside. Continue to the next hallway and defeat all enemies. Once clear, approach Eva's painting to obtain the Osiris. Use it to kill the enemies in the room. After dealing with them, head back to the hallway and destroy the white barrier to reach a room with a Lost Soul above the doorway and more red orb sacs.
Head outside and jump on the platforms to reach the next door. Slice through the blue webs then before moving forth, turn to the corridor to the right to find another room with a Lost Soul and a Copper Door. Reaching this room can take a few attempts since you need to perform a long double-jump with a timed air dash. (If you're having difficulties reaching it, wait until you get the Angel Boost ability) You can't open the copper door for now so just leave it.
Follow the hallway then smash the door open. Head to the library and step on the glowing circle on the floor for another flashback. Continue to the edge of the platform to acquire the Ophion Angel Lift. This will pull Dante towards enemies or objects. Use the Angel Lift to swing your way across the the platforms and kill enemies that you encounter. Continue until you reach the other base of the chains and destroy it.
After returning, kill the enemies in the room then leave the hall for another scene. Follow the straightforward path until you reach the last hallway leading to the exit. Reach the marker to escape the area and complete the mission.