How To Unlock Secret Boss In Deltarune Chapter 5—Where To Use Mystery Key

Chapter 5 of Deltarune is finally here, and just like with other chapters of the game, there’s another secret boss to discover and battle.

As has been the case in the past, it’s quite the task to reach the boss, let alone acquire the Mystery Key to unlock it. You’ll need to gather some rare collectables and follow a specific path to find the entrance, but it’s easy to get lost in the new Flower World.

Worry not, though, as we’ve got it all laid out for you. Here’s how to get the Mystery Key, as well as where to use it to unlock the secret boss of Deltarune Chapter 5.

How To Unlock The Mystery Key In Deltarune Chapter 5

If you want to unlock the secret boss of Deltarune Chapter 5, you’ll first need to acquire the Mystery Key.

Finding the Mystery Key is easy; it’s a purchasable item in the Shop in the Cliffs area. Just use any fast-travel door and select Cliffs, then Shop.

That said, you’ll realise you need a special currency to buy the Mystery Key: Pink Coins. You need 10 to buy the Key, and there are 19 in total across the level. You’ll find them scattered throughout the Flower World, often in chests for completing secrets and puzzles.

Keep your eyes peeled throughout your playthrough, but once you’ve found at least 10, you can buy the Mystery Key and begin your journey to the secret boss of Deltarune Chapter 5.

Where To Find The Secret Boss In Deltarune Chapter 5

Once you’ve got the Mystery Key, you’ll need to find the Pink Door, and the journey begins at Green’s Shop.

From Green’s Shop, head to the right, hit the perspective shift switch, and jump all the way to the top of the area. Once you’ve reached the top, go left.

Here, you’ll have to do a bit of platforming to reach the other side by using your sword to bounce across the flowers as they move. It might be a bit tricky, but should you fall, you’ll only take a small amount of damage—though you will be placed back at the beginning of the section.

Once you see the first chance to drop down, do so, and you’ll find a room with a green pinwheel. Activate it, and you’ll begin to slowly descend through a variety of obstacles. Dodge and weave as you fall, whilst slashing the blue flowers to make space for your Soul to squeeze through the gaps.

At the very bottom, you’ll enter a new area, with a large pink door—this is where you’ll find the secret boss! Use your Mystery Key on the locked door, and head inside for the secret boss. Or, if you’re not quite ready, you’ll find another fast-travel access point here, too, so you can come back with ease at any time.

For the full video walkthrough, check out the video below by MonkeyKingHero:

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