Deltarune Chapter 3 Secret Boss Guide
In Deltarune Chapter 3, unlocking and defeating the secret boss is one of the most rewarding challenges for players. To find the secret boss, you'll need to achieve S-ranks during Tenna’s game show, which unlocks access to the “S” labeled door leading to the secret minigame.
Here, you can acquire crucial items like the Ice Key, Shelter Key, and eventually the Shadow Mantle, which is essential to survive the secret boss battle against The Knight. Make sure to equip the Shadow Mantle to protect yourself from the Knight’s one-hit KO attack. This guide will walk you through how to obtain all the necessary keys, unlock the secret boss, and survive the intense fight.
Is There a Secret Boss in Deltarune Chapter 3?
Yes, there is a secret boss in Deltarune Chapter 3, and unlocking it requires completing a few specific steps. As is typical for Toby Fox's games, you won’t get a hint unless you dive deep into the game’s exploration.
Unlike the main story bosses, this one is hidden behind some interesting challenges, and defeating it will reward you with powerful items, like the Shadow Mantle, that are crucial for your progression.
How to Get the Shadow Mantle in Deltarune?
The Shadow Mantle is a crucial item needed to defeat the secret boss in Deltarune Chapter 3. Here’s how to get it:
Step 1: Find the Ice Key
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During the first minigame, you’ll play as Kris without Susie or Ralsei.
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You’ll need to level up Kris by defeating enemies to unlock the Ice Key.
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The key is hidden in a treasure chest, and you can find it after leveling up Kris to level three.
Step 2: Find the Shelter Key
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After obtaining the Ice Key, you need to achieve another S-rank in the second round of the game show.
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Once completed, you will be able to enter the secret minigame again and earn the Shelter Key by exploring the map and defeating enemies to level up Kris to level two.
Step 3: Find the Shadow Mantle
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After securing both the Ice Key and Shelter Key, head into the third round of the game show and complete the final S-rank challenge.
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Completing this final challenge unlocks the Shadow Mantle, an essential item that grants protection during the secret boss battle. Without it, you’ll be wiped out with a one-hit attack.
What Are the Tips for Beating the Secret Boss?
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Level up: Before heading into the secret boss fight, make sure your character is leveled up. You can do this by defeating enemies during the minigame to gain experience.
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Use Healing Items: Bring plenty of healing items with you. The Knight can deal heavy damage, so be prepared for a long, tough battle.
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Master Dodging: Learn the Knight’s attack patterns and practice dodging to avoid damage. Patience is key during this fight.
Deltarune Chapter 3 Release Time and Platforms
Deltarune Chapter 3 will be available across multiple platforms, including Steam (PC), PS4, PS5, Nintendo Switch, and Nintendo Switch 2. With the release of the Switch 2 on the same day, Deltarune will serve as one of its major launch titles. Players in Japan, Australia, and New Zealand will get the game on June 5, 2025, due to their time zone differences, but the release is global.
Here are the release times by region:
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US West Coast: 8 AM (June 4, 2025)
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US East Coast: 11 AM (June 4, 2025)
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United Kingdom: 4 PM (June 4, 2025)
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Central Europe: 5 PM (June 4, 2025)
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Japan: Midnight (June 5, 2025)
For Switch 2 users, the game will unlock at midnight local time on June 5, which is great for eager players wanting to jump in as soon as the game becomes available.
Deltarune
Deltarune is an episodic role-playing video game developed by Toby Fox as a follow-up to his critically acclaimed 2015 title, Undertale. In Deltarune, players control Kris, a human teenager who, alongside Susie, a monster, and Ralsei, a prince from the Dark World, embarks on a journey to save the world.
The group must seal the Dark Fountains, which are prophesied to end the world. Throughout their adventure, the group encounters both allies and adversaries, making for a rich and dynamic experience.
