In Citadelle des Morts, the only way to obtain PHD Flopper is through the Wonderfizz. However, there’s an Easter Egg that allows you to get this popular perk for free.

To unlock it, you need to collect three alcohol bottles. Interact with the bottles to pick them up. These bottles can be found in the following locations:

• Undercroft
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• Dining Hall
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• Alchemical Lab
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Once you’ve collected all three bottles, head to the tavern and approach the bar. On the bar, you will now see the three bottles, each with a filled glass beside it.

Wait until the new round starts, then interact with the serving tray.

Once you interact with it, you will no longer hold a weapon in your hands. Your task now is to serve the zombies that come to the bar with their desired drink. Colored circles will appear in front of the zombies, indicating which of the three drinks they want.

Interact with the corresponding glass and place it in front of the zombie (interact again).

Once you’ve successfully served all the zombies, you will be rewarded with the PHD Flopper perk.