How to defeat Roaring Knight secret boss fight in Deltarune Chapter 3

The Roaring Knight in Deltarune Chapter 3 is a brutal secret boss who appears after the Teena fight near the end of the chapter. This isn’t a gimmick fight — it’s a punishing test that demands the right preparations, equipment, and timing. Without the Shadow Mantle, this boss will obliterate your team in a matter of turns.

This guide breaks down how to defeat the Roaring Knight in Deltarune Chapter 3.

Note: This guide is based on the writer’s experience; your gameplay may vary slightly.

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How to beat the Roaring Knight in Deltarune Chapter 3

Duel with the boss (Image via Toby Fox/Youtube@/Xirez)

The Roaring Knight strikes right after the Teena boss fight, with no downtime in between. So, save your game before triggering the end sequence and only engage him after getting the Shadow Mantle — this fight is unwinnable without it.

Make sure your team is equipped properly before heading into this fight. Here's the ideal setup:

• Susie: Shadow Mantle, Jevilstail, Toxic Axe
• Kris: Saber10, Spikeband, Twin Ribbon
• Ralsei: Dealmaker, Flex Scarf, Twin Ribbon

Susie handles the front line with Shadow Mantle and Toxic Axe, while Kris and Ralsei focus on support, status, and healing (Ralsei's dual healing is pretty good).

Let’s break down what happens in the fight and how to counter the boss:

• Before facing the Roaring Knight, make sure Susie is equipped with the Shadow Mantle. Without it, she’ll go down in a couple of hits.
• The boss's Ice Crystal Barrage is a low-damage move but fast enough to mess up your rhythm if you’re not watching closely. Dodge diagonally to slip between the crystals. This is followed up by Gaster Sword Blasters, a near-instant wipeout attack if you don’t time your dodge perfectly — this move alone makes the fight infamous.
• The Roaring Knight also uses Lemonbread Slash, which comes out fast and deals massive damage. It’s the most punishing of the normal slashes and hits hard. His Swords’ Dance attack is the trickiest; dodging this move is borderline impossible, so just prepare to tank it with healing support.
• Finally, there’s a basic slash attack that’s slow and easy to avoid — this is your only breathing window, so use it to heal or set up buffs. Your goal is to deal damage worth at least 25% of the boss's HP to end the fight.

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Getting the Shadow Mantle: The key to beating the boss

To get the Shadow Mantle in Deltarune Chapter 3, you must:

• Get an S Rank on the first Board.
• Complete the backstage mini-game to level up and obtain the Ice Key.
• Get an S Rank on the second Board.
• Use the Ice Key to enter the temple, get the White Cloak, and unlock the dark zone.
• Find the Shelter Key, then return to the Green Room.
• Play the final mini-game with Susie and Ralsei, unlock the Shelter, and fight the Shadow Mantle mini-boss. Win that fight and you’ll get the Shadow Mantle — the only thing that gives you a real chance against the Roaring Knight.

Note: These steps provide a summarized overview of how to obtain the Shadow Mantle and are not intended as a full, detailed guide.

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Rewards

A Shadow Crystal drops when Susie knocks a shard off the boss's blade, and the Black Shard, a powerful weapon for Kris that excels against Dark-element enemies (Image via Toby Fox/Youtube@/Xirez)

Defeating the boss in Deltarune Chapter 3 gives you:

• Shadow Crystal
• Black Shard

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This concludes our guide to beating the Roaring Knight in Deltarune Chapter 3.