Deltarune Chapter 3 introduces a significant escalation in challenge through its secret boss, the Roaring Knight. Unlike previous secret encounters like Jevil or Spamton NEO, this battle is heavily integrated into the chapter’s progression and requires a series of specific prerequisites to even survive the first few turns. The Roaring Knight represents a massive spike in difficulty, characterized by high-speed bullet patterns and a unique status effect that can cripple a party's healing capabilities. Success in this encounter depends less on raw luck and more on meticulous preparation, specifically regarding the acquisition of the Shadow Mantle and the optimization of equipment from previous chapters.

Unlocking the Path to the Secret Boss

The road to the Roaring Knight begins long before the final curtain call of Chapter 3. To challenge this boss effectively, a player must first navigate the intricacies of Mr. Tenna’s game show boards. The secret boss is technically an optional encounter that occurs after the main confrontation with Mr. Tenna, but without the proper items, it is an exercise in futility. The primary objective is to obtain the Shadow Mantle, a piece of armor that provides essential elemental resistance against shadow and star-based attacks, which constitute the bulk of the Knight’s offensive kit.

Achieving S-Rank on Tenna’s Boards

Access to the necessary keys for the Shadow Mantle is gated behind S-rank performances on Mr. Tenna’s mini-game boards. This requires a high level of precision in the following areas:

  1. Board 1 (Cooking Segment): To secure an S-rank here, you must collect all four keys scattered throughout the environment and maintain a near-perfect score in the cooking mini-game. Once achieved, the S-rank door in the green room becomes accessible. Inside, a console mini-game awaits. You must find the controller on the right side of the room, interact with the board, and level up to level 3 by clearing enemies and cacti. This leads to a red chest containing the Ice Key.

  2. Board 2 (Concert Segment): This board requires gathering all hidden photos and participating in the "Moss Eating" event. Achieving an S-rank here unlocks the second phase of the console mini-game. Utilizing the Ice Key, players can access an icy castle dungeon. Navigating this area involves a rafting segment and a maze where following the path of a mysterious white cloak is the only way to progress. Successful completion rewards the player with the Shelter Key.

The Shadow Mantle Mini-Boss

With both the Ice Key and the Shelter Key in hand, the final step before the Knight is the confrontation with the Shadow Mantle itself. This is a mini-boss encounter located within the shelter unlocked by Toriel’s assistance late in the chapter.

The Shadow Mantle boss features four distinct phases. In the early phases, it relies on Bomb Attacks (exploding in straight lines) and Fireball Attacks (randomized projectiles). As the fight progresses, it introduces Meteor Attacks that sweep vertically across the screen. The strategy here is relatively straightforward: maintain distance during fireballs and stand at diagonal angles to the bombs. Defeating this entity grants the Shadow Mantle armor, which must be equipped on Susie to maximize her survivability and her Rude Buster damage output in the upcoming Knight fight.

Mechanics of the Roaring Knight Encounter

The Roaring Knight appears after the defeat of Mr. Tenna. While the story progresses regardless of the outcome of this fight, a "defeat" typically occurs quickly for unprepared players. The Knight’s introduction is marked by red blade-like shadows and a sudden shift in the environment.

The Swoon Status Condition

The most punishing aspect of the Roaring Knight battle is the Swoon status. When a party member's HP drops to zero, they are not merely downed; they are inflicted with Swoon. This sets their HP to -999 (or -80 for Kris), effectively disabling passive HP regeneration. Standard healing items that do not possess "reviving" properties are useless in this state. Because of this, the inventory must be stocked with Revive Mints and Revive Dust. Relying on Ralsei’s Heal Prayer becomes a secondary strategy, as preventing the Swoon status is more efficient than trying to recover from it.

Damage Thresholds and Mercy

It is important to note that the Mercy bar for the Roaring Knight is crossed out. A pacifist victory in the traditional sense is not possible through the Spare command. However, you do not need to fully deplete the Knight’s massive health pool to win. Dealing damage equal to approximately 25% of his total health will end the encounter successfully. This makes Susie the MVP of the fight, as her Rude Buster is the most consistent source of high-magnitude damage.

Optimal Party Loadouts

To withstand the Knight’s relentless star and shadow barrages, a defense-heavy build is recommended. This often requires utilizing items found in Chapter 1 and Chapter 2.

Kris: The Support/Tank Hybrid

  • Weapon: Bounce Blade (Chapter 2). While it offers a lower attack boost, its passive defense increase is vital for keeping Kris alive to use items.
  • Armor 1: Twin Ribbon (Chapter 2). This item increases the grazing area by over 50%, allowing the party to generate TP safely from the Knight's dense bullet patterns.
  • Armor 2: Jevilstail (Chapter 1). Obtained by pacifying Jevil, this provides a well-rounded boost to Attack, Defense, and Magic.

Susie: The Primary Damage Dealer

  • Weapon: Toxic Axe (Chapter 3). This is the strongest available weapon in the current chapter and significantly boosts the potency of Rude Buster.
  • Armor 1: Dealmaker (Chapter 2). Dropped by Spamton NEO, this provides high defense and a substantial magic boost, directly scaling Susie’s special attacks.
  • Armor 2: Shadow Mantle (Chapter 3). As mentioned, this is mandatory to reduce the elemental damage Susie takes, ensuring she stays on the field to deal damage.

Ralsei: The Dedicated Healer

  • Weapon: Fiber Scarf (Chapter 2). It provides a balanced stat spread, allowing Ralsei to contribute small amounts of damage when TP is high and healing isn't immediately necessary.
  • Armor 1: Tenna Tie (Chapter 3). Found in the Green Room’s ball machine, this offers a massive +5 Defense boost. While it reduces Magic slightly, Ralsei’s survival is more important than the potency of individual heals.
  • Armor 2: Royal Pin (Chapter 2). A reliable source of +3 Defense and +1 Magic.

Combat Strategy and Attack Patterns

The Knight’s attacks are fast-paced and require high reaction speeds.

  1. Gaster Sword Blasters: These are the most dangerous attacks in the Knight’s repertoire. They cover large portions of the screen and can potentially one-shot a character not wearing the Shadow Mantle. The key is to watch the telegraph lines and move to the furthest corners of the bullet box.
  2. Lemon Bread Slash: A complex pattern that deals significant damage but rarely results in an immediate KO unless the character was already weakened. It is best to graze the edges of these slashes to build TP for a subsequent Heal Prayer.
  3. Swords’ Dance: The Knight circles the soul with spinning blades. This requires precise, circular movement within the box. It is often better to take one hit and use the resulting invincibility frames to reposition rather than getting trapped in a multi-hit loop.

During the fight, Kris should focus on using items (Revive Mints) or X-Slash if TP is overflowing. Ralsei should be constantly scanning for opportunities to use Heal Prayer. Susie should spend every available point of TP on Rude Buster. If the party’s HP is stable, grazing the Knight’s star projectiles is the fastest way to maintain the offensive momentum.

Rewards and Post-Game Impact

Upon successfully surviving the encounter and dealing the required 25% damage, the Roaring Knight will retreat, leaving behind two essential items: the Black Shard and the Shadow Crystal.

  • The Black Shard: This is a powerful new weapon for Kris. It deals bonus Dark and Star damage. Lore-wise and mechanically, it appears to be a top-tier option for the upcoming challenges in Chapter 4, particularly for rumored encounters against enemies like Mike.
  • The Shadow Crystal: Similar to the crystals obtained from Jevil and Spamton NEO, this item seems to be part of a larger questline involving Seam in Castle Town. Collecting all Shadow Crystals is widely theorized to be the requirement for the game’s ultimate equipment or a hidden ending.

Defeating the Roaring Knight does not lock you out of a pacifist run. Even though the combat is violent by necessity, the game treats the victory as a tactical survival rather than a lethal execution. Players can proceed to Chapter 4 with their pacifist streak intact, carrying the Black Shard as a testament to their mastery of Chapter 3’s most difficult secret.