If you want to leave Oogles a tip for writing this Castlevania: Lords of Shadow 2 guide you can do so here.
Castlevania: Lords of Shadow 2 Walkthrough Arts District IV
Castlevania: Lords of Shadow 2 Arts District IV
Follow Viktor down the path and towards the platform below, then flip the power switch and head through the door.
To those who played the first Lords of Shadows DLC, I seem to remember being promised having an easier life as a vampire... Anyways since you can't jump the gap, turn right and climb up on the ladder then jump from the catwalk and turn into mist to get propelled forward and towards Viktor.
Now once again head right and jump onto the wooden beam, then make your way to where Viktor is standing, then head inside the elevator and operate it.
Once you're outside Zobek's lieutenant will rejoin you and you'll be attacked by a lot of possessed and Satans Soldiers. Luckily the other two will help you and you can even sit back and let them kill the enemies.
With Viktor dead, you'll receive the last piece that you need to complete the mirror of fate.