This guide shows how to unlock the Secret Mystery Box in “Prologue” and “Groesten Haus” in Call of Duty WW2 Zombies. It’s very useful for the Pressure Cooker trophy & achievement (beat round 20 in Prologue).
There are 10 lanterns located around this map that you must shoot: 8 are inside the house (4 downstairs, 4 upstairs) and 2 are outside (left window, right window). When shooting the lanterns they make a raven sound and will start glowing purple.
After shooting all 10 lanterns a door opens upstairs, revealing the secret Mystery Box behind it. It costs 1000 points to use and gives you one random weapon. It can also give you Jack-in-the-Box which distracts zombies for a few seconds and kills them upon detonation. You can use the mystery box as often as you want.
The video shows all 10 lantern locations.
Here are screenshots of all 10 lantern locations:
And that’s all you need to do to unlock the Myster Box. It can be done at the start of the match right away. For surviving until round 20 (Pressure Cooker trophy) you need to run around the map in circles to train the zombies (so they are running in one line). This reduces the risk of getting cornered by the zombies. The mystery box makes it a lot easier. Especially when you use your freefire perk you should always have an MG ready to spray infinite ammo for a few seconds.