Granblue Fantasy Relink: Endless Ragnarok Boss Guide - Defeat Seofon & Tweyen

Master the Fatebreaker clash against Seofon and Tweyen with our comprehensive Endless Ragnarok boss guide for Granblue Fantasy: Relink.

The massive expansion to Granblue Fantasy: Relink has finally arrived, bringing a brutal step-up in endgame difficulty that will push even the most seasoned skyfarers to their absolute limits [1]. If you are jumping into this fresh wave of content, you will quickly realize that the expansion's initial hurdle requires a highly optimized strategy, which is why having a reliable endless ragnarok boss guide is essential to surviving the onslaught [1]. This guide focuses on the "Fatebreaker" quest, a mechanically dense double-boss battle against two legendary Eternals: Seofon (Siete) and Tweyen (Song) [1].

In this endless ragnarok boss guide, we break down the core mechanics of the fight, analyze the dual-threat health pool, and detail how to navigate the devastating team-wipe abilities of both bosses [1]. Additionally, we will look at how the expansion's newly introduced Master Traits system can be used to optimize your characters so you can secure that coveted S+ rank [1, 2]. For those looking to dive deeper into the patch notes and official announcements, check out the Granblue Fantasy: Relink Steam Community Hub for the latest developer updates and game installation kits [1].

The Fatebreaker Battle: Boss Overview

Unlike standard multi-boss fights where players can defeat enemies one by one, Seofon and Tweyen share a single, unified health bar [1]. No matter which Eternal you attack, you deal damage to the same pool [1]. However, simply hitting whoever is closest is a recipe for disaster. The key to this fight lies in managing their unique mechanics, particularly Tweyen's "Inner Monster" phase [1].

Boss Profile & Core Mechanics

Boss	Primary Threat	Key Mechanics to Watch	Priority Level
Tweyen (Song)	Ranged barrage, tracking shots, and debuffs [1, 2]	Echo String Rites (Charges her Inner Monster bar) [1]	High (Must be interrupted or managed) [1]
Seofon (Siete)	High-speed melee, physical AoEs, and sword summons [1, 2]	Synergy of Star and Crown (Timed crystal phase) [1]	Medium (Focus during specific transitions) [1]

Community reports highlight that while Seofon's sword attacks are flashy and dangerous, Tweyen acts as the silent party-wiper if left unchecked [1]. Therefore, your primary target for the majority of the first half of the fight should be Tweyen [1].

Phase 1: Managing Tweyen's Inner Monster

At the start of the fight, Tweyen will begin channeling her Echo String Rites [1]. This is a charging phase indicated by a bar on the screen [1]. If the bar fills completely, she unleashes her "Inner Monster," entering a relentless, highly aggressive state that forces your team onto the defensive [1].

Interruption and Mitigation

When you first tackle this quest with entry-level Fatebreaker gear, completely preventing the Inner Monster phase is nearly impossible [1]. However, continuing to attack her has a dual purpose:

Interrupting: If your team's DPS is exceptionally high, you can delay or temporarily halt the charge [1].
Depleting the Bar: Once the Inner Monster is active, hitting Tweyen directly depletes her Inner Monster bar [1]. The more aggressively you attack her during this dangerous phase, the faster she will return to her normal state [1].

Surviving "Asteroid Jaeger"

When Tweyen enters her Overdrive state, she will cast Asteroid Jaeger [1]. This is a massive bullet-hell phase that requires precise movement [1].

The Strategy: Do not try to attack. Instead, toggle your sprint and prepare to dodge sequentially [1].
The Finisher: Watch out for a massive purple explosion at the very end of the barrage [1]. This explosion signals the end of the phase and opens up a brief DPS window where you can safely punish her [1].

Phase 2: Seofon's Entry & The Star and Crown

After surviving the initial onslaught and breaking Tweyen's Inner Monster bar, Seofon will step forward, and Tweyen will temporarily retreat [1]. This shifts your targeting priority entirely to Seofon [1].

[Tweyen Retreats] ──> [Seofon Steps In] ──> [Synergy of Star and Crown Cast] ──> [Destroy Ground Arrows & Crystal]

Synergy of Star and Crown

This is the signature mechanical check of the fight [1]. A large timer bar will appear in the center of the screen, representing the charging of the Wrath of Star and Crown [1].

To successfully bypass this mechanic:

Destroy the Arrows: You must clear the glowing arrows on the ground while simultaneously dodging incoming tracking attacks [1].
Shatter the Crystal: Direct all heavy skills and combo finishers toward the central crystal before the middle bar fills up completely [1].
Avoid the Red Zones: Failing to dodge the red area-of-effect markers during this phase will instantly fail the side goal for your entire party [1].

Phase 3: Surviving "Smus" and Utilizing New Mechanics

As the fight enters its final stretch, both Eternals will fight simultaneously, leading to the most difficult dodging sequence in the encounter: Smus [1].

How to Dodge Smus

Step	Attack Pattern	Required Action
Step 1	Multiple intersecting linear grid lines on the arena floor [1].	Walk or light-dodge out of the red indicators [1].
Step 2	A massive, expanding circular shockwave from the center [1].	Time your jump to leap clean over the ring [1].
Step 3	Rapid tracking shots targeted directly at individual players [1].	Execute a Perfect Dodge or use a high-frame counter-attack [1].

Unleashing Summons and Primal Bursts

Endless Ragnarok introduces powerful new combat systems that are crucial for trivializing the final 20% of the bosses' health bar [1]:

Co-op Summons: You can now summon giant beasts (such as a Griffin) [1]. While active in summon form, your character is completely immune to damage, allowing you to ignore complex boss mechanics and deal massive DPS safely [1].
Primal Bursts: Triggering Link Time and immediately chaining all four players' Skybound Arts (SBA) activates a Primal Burst [1]. This calls forth a legendary entity—such as Bahamut casting Catastrophe—to deal millions of damage and break the bosses out of Overdrive [1].

Build Optimization: Master Traits & Gear

To consistently clear the Fatebreaker quest under the 10-minute mark and secure an S+ rank, you must utilize the new Master Traits system [1, 2]. Unlocked at level 100, Master Traits allow characters to specialize into three distinct styles: Insight, Essence, and Crux [2].

For this specific fight, having characters with defensive or utility-focused Master Traits can save your run [2]. Below is a comparison of optimal styles for key characters in this encounter:

Recommended Master Styles for Fatebreaker

Character	Optimal Style	Key Perk Benefit	Why It's Great for This Fight
Gran / Djeeta	Essence (Combat Healer)	Revive rescues allies globally, granting ATK↑ & DMG Cap↑ [2].	Keeps the team alive during bullet-hell phases without losing DPS [1, 2].
Siegfried	Insight (Perfect Striker)	Dragonsbane Pulse builds up to lvl 7, making all attacks perfect executions [2].	Provides steady, high-damage output to quickly deplete the Inner Monster bar [1, 2].
Vane	Essence (Team Player)	Shortens skill cooldowns for all allies inside his Rampart shield [2].	Allows the team to stand completely safe inside the invincibility dome during Smus [1, 2].
Cagliostro	Crux (Alchemedic)	Excess healing from Reinforce is converted into a sturdy Shield [2].	Provides a massive HP buffer to survive unexpected tracking shots [1, 2].

Battle Reward Table

Clearing this fight on Chaos difficulty rewards players with some of the most powerful endgame sigils in the expansion [1, 2].

Reward Item	Drop Rate	Primary Effect
Damage Cap V+	Common	Increases the damage ceiling of your attacks, allowing for extra bonus stats [1].
Stout Heart Sigil	Uncommon	Prevents interruption from enemy attacks and reduces damage taken [1].
Fatebreaker Upgrade Materials	Guaranteed	Used to transcend weapons and level up Style Ranks [2].

Frequently Asked Questions

How do I unlock the Seofon and Tweyen fight in Endless Ragnarok?

To unlock this fight, you must reach Level 100, complete the main story of the Endless Ragnarok expansion, and unlock the Fatebreaker tier of quests, starting at Chaos difficulty [1, 2].

Can I play cross-play with friends for this boss fight?

Yes! One of the major features of the Endless Ragnarok expansion is full cross-play support across PC, PlayStation, and the new Switch 2 console, allowing you to team up regardless of platform [1].

What is the best strategy for the "Synergy of Star and Crown" phase?

According to our endless ragnarok boss guide, you must split your party [1]. Have your ranged characters focus on clearing the arrow indicators on the floor while your heavy melee DPS characters focus down the central crystal before the timer bar in the middle of the screen fills up [1]. Avoid getting hit by the red indicators to preserve your party's side goals [1].