Grab the red orb from the previous step and place it on the spawn map (hanging on the wall).
Activate the Kronorium and chase the ghost bird back to the prison.
The location of where the bird goes may vary. You will need to use the Spectral Shield to see the bird, but there are several locations including. Note: On the 4th bird, you can only see the bird in Zombie Blood. Listen out for the bird or the Warden crying to locate the area of the bird. Use the number 8-7-2 on the number generator in the Citadel Tunnels to obtain the Zombie Blood. Instead of the shield, throw your Hell's Retriever/Redeemer at the bird and it will drop the Kronorium which you can then pick up.
There are 40 possible locations (20 currently listed):
Richtofen's Laboratory 2nd floor
West Grounds truck
Recreation Yard on a tall rock
Cell Block 2nd floor volt meter (where Electric Cherry used to be)
Cell Block near Monkey Bomb statue under 2nd Wolf Head
Library top of bookshelf
Michigan Avenue across Warden's Office entrance
Time's Square above Cafeteria entrance
Showers near washing machine
Warden's Office entrance
Warden's Office above fireplace
Warden's Office outside on balcony
Citadel Tunnels as you go down from Warden's Office
Call of Duty Zombies (CODZ) is a fan-managed gaming community centered around the popular Call of Duty franchise with central focus on the Zombies mode. Created in 2009, CoDZ is the ultimate platform for discussing Zombies theories, strategies, and connecting players.