As soon as the mission
starts, jump on the platform and take the path to the left. Make sure to take your time and above the deadly soul stream erupting from below. After swinging to the platform with a wall, check the back to find a lost soul.
You can restart the level to avoid having a death penalty to your evaluation at The End
of the mission
. From the starting position, take the right path this time and defeat the hell and frost knights. Look to the left to find a demon pull target across. Boost there and pull the wall to remove it then quickly use angel lift to reach that platform. You'll find another soul there.
Make your way to the main platform where you'll have to fight two waves of enemies. After clearing them, check the corner near a green health sac to find a lost soul.
From that platform, head to the other side and jump on a few more platforms. Find an angel lift target to the right which leads to a cavern near the walls. Swing there to find an angel web. Destroy it and you'll find the ivory key at The End
Backtrack to the main path and continue until you encounter two enemies. Take them out then use angel lift and demon pull to access the floating platforms and arrange them so you can reach the platform with a divinity statue on it. Swing to the other platform and defeat the enemies. Look up on the wall to find another lost soul.
From that same platform, look over the edge to find a demon pull target. Use it to create a platform leading to a Gold Door. (Gold - A Day in Hell)
Continue forth and after boosting the second time, turn around to find a large devil trigger star in the small platform behind. After getting it, return to the previous platform then continue to the next one. Cross floating bridge, destroy the angel barrier along the way and finally pull the weakened pillars of the large platform ahead to clear the path. Jump in there are prepare for an enemy ambush.
After defeating the three waves of dangerous enemy compositions, wait for the soul stream to finish erupting then swing to the last platform. However, don't leave yet. Instead, look behind the large rock to the right to find a lost soul.
Continue swinging across to complete the mission