where to use mystery key deltarune chapter 5

Use the Mystery Key at the locked pink door near the end of the Chapter 5 secret route. The current guides say you buy the key from the Cliffs shop with 10 Pink Coins, then backtrack to that pink door to open the path to the secret boss area.

Where it goes

• Get 10 Pink Coins.
• Buy the Mystery Key at the Cliffs shop.
• Continue through the late-game platforming route.
• Find the locked pink door and use the key on it.

What it unlocks

That door leads into the hidden boss path, so the key is not used on a normal story door or shop entrance; it is specifically for the secret-route pink door.

Quick note

Public reports are consistent on the main route, but some details about the exact pathing vary a little by guide, so the safest answer is: save the key for the pink door near the chapter’s end.

Would you like the step-by-step route to the door?