Endless Ragnarok Seofon Tweyen Boss Guide: How to Beat the Eternals

Master the ultimate challenge in Granblue Fantasy Relink. Our Endless Ragnarok Seofon Tweyen boss guide covers phase mechanics, DPS tips, and rewards.

The massive expansion to Cygame's hit action RPG has finally arrived, bringing intense endgame challenges that will push your crew to its absolute limits. If you are struggling to survive the trial of the Eternals, our comprehensive endless ragnarok seofon tweyen boss guide is here to help you conquer this brutal encounter. In this guide, we will break down the mechanics of this shared-health battle so you can claim your S+ rank rewards. To learn more about the base game and its updates, you can check out the official Granblue Fantasy Relink website for patch notes and character details.

Boss Overview and Elemental Matchups

Before stepping onto the battlefield, it is crucial to understand who you are fighting and how to optimize your party setup. Seofon and Tweyen are legendary members of the Eternals, and they do not hold back.

Unlike standard double-boss encounters where you must deplete two separate health bars, Seofon and Tweyen share a single, unified health pool. Any damage dealt to either boss directly reduces their collective health bar. However, their elemental strengths and weaknesses differ significantly, making party composition a key factor in your success.

Elemental Strengths and Weaknesses

Boss	Voice Actor	Elemental Weakness	Elemental Resistance
Seofon	Junichi Suwabe	Fire	Earth
Tweyen	Yūko Minaguchi	Fire	Earth

Because both bosses are highly susceptible to Fire-element attacks, slotting Fire-attribute characters like Percival, Zeta, or Gran/Djeeta (Fire build) into your party will drastically increase your damage output. Conversely, avoid relying heavily on Earth-attribute damage, as both bosses possess high resistance to it.

Phase 1 Strategy: Managing Tweyen’s Inner Monster

When the battle begins, both bosses will be present, but player experience strongly suggests focusing your initial offensive efforts on Tweyen. Managing her unique mechanics is the key to surviving the opening minutes of the fight.

The Echo String Rites and Inner Monster Gauge

At the start of the fight, Tweyen will begin channeling an ability called Echo String Rites. This acts as a charging phase. If the gauge fills completely, she unleashes her "Inner Monster," entering an empowered state where she attacks relentlessly with highly aggressive, tracking projectile patterns.

While it is theoretically possible to interrupt the Echo String Rites by dealing a massive threshold of damage quickly, players running the encounter with fresh expansion gear will find it almost impossible to prevent the first activation. The gauge even resumes charging from where it left off if briefly interrupted.

When her Inner Monster state inevitably activates, your focus must shift. While you need to play defensively to dodge her tracking shots, you must also maintain consistent DPS. Dealing damage to Tweyen during this phase actively depletes her Inner Monster bar, forcing her back into her normal state.

Key Attacks in Phase 1

Attack Name	Visual Tell	Survival Strategy
Echo String Rites	Tweyen channels a glowing energy circle	Focus all DPS on Tweyen to delay or attempt to interrupt the cast.
Asteroid Jagger	Red ground indicators and falling projectiles	Sprint in a wide circle and use perfect dodges. Watch out for the massive purple explosion at the very end.
Stink of Thunder	Tracking purple lightning shots	Highly aggressive tracking. Activate defensive buffs like Stout Heart or damage cuts, and dodge precisely.

Phase 2 Strategy: Synergy of Star and Crown

Once you deplete a portion of their shared health bar, Seofon will step forward while Tweyen retreats, initiating a major mechanical transition. This phase introduces a strict DPS check that can easily wipe unprepared parties.

Clearing the Star and Crown Arrow Trial

Seofon will trigger a phase called Synergy of Star and Crown. During this event, a large progress bar appears in the center of the screen, slowly filling up. Multiple arrow-like crystal structures will spawn across the arena floor.

To successfully bypass this mechanic, your party must destroy all of these arrow crystals before the central timer bar fills completely. Failing to do so, or getting hit by the red hazard zones and falling projectiles during the trial, will cause you to fail the "Wrath of Star and Crown" side goal, ruining your chances of securing an S+ completion rank.

Step-by-Step Star and Crown Strategy

Spread Out: Have your party members split up to cover different quadrants of the arena.
Prioritize Clusters: Destroy the closely grouped arrow crystals first using wide-reaching AoE skills.
Dodge the Red Zones: Do not get greedy. If a red circular indicator appears beneath you, dodge immediately. Getting hit stuns you and wastes precious seconds.
Save High-Damage Skills: Keep a few fast-activating offensive skills off cooldown specifically to burst down the final crystals.

Phase 3 Strategy: Seofon’s Onslaught and Summons

After surviving the Star and Crown trial, Seofon becomes the primary target on the stage. Because you are forced to focus on Seofon, Tweyen will eventually gain her Inner Monster state automatically in the background. This is the most chaotic portion of the fight, but the expansion introduces powerful new tools to help you pull through.

Utilizing the New Summon Mechanic

Endless Ragnarok introduces a powerful companion summon mechanic. When both bosses begin overlapping their most dangerous attacks, activating your summon (such as a giant Griffin or a Mechanized Executioner) is highly recommended.

While active, your summoned beast grants you temporary invincibility, allowing you to ignore incoming projectile spam and focus entirely on dealing massive, uninterrupted damage to Seofon.

Dodging "Smus"

Seofon's most notorious signature attack in this phase is Smus. It is widely considered by the community to be one of the most difficult attacks to avoid in the entire expansion.

Smus Attack Wave	Attack Pattern	How to Dodge
Wave 1: Grid Lines	Glowing red lines crisscross the arena	Stand in the safe gaps between the intersecting lines.
Wave 2: Central Ring	A massive expanding ring of energy from the center	Time a jump to leap cleanly over the expanding shockwave.
Wave 3: Final Sweep	A rapid, full-arena tracking slash	Requires a frame-perfect dodge or a well-timed counter-attack skill.

Phase 4 Strategy: Primal Burst and the Final Push

When the bosses drop below 20% health, they will enter a desperate, highly defensive state, often gaining temporary invincibility frames. To break through their final defenses, you must coordinate your Skybound Arts (SBA) to trigger a Primal Burst.

How to Trigger Primal Burst

Build the Link Gauge: Maintain continuous attacks and perform Link Attacks to trigger Link Time, which slows down the bosses.
Chain Your SBAs: Once Link Time is active, have all four party members unleash their Skybound Arts in rapid succession to initiate a full chain.
Unleash the Primal Burst: Completing a 4-chain SBA during Link Time triggers a Primal Burst, summoning a massive entity (such as Bahamut Catastrophe) to deal millions of bonus damage, bypassing the bosses' defensive buffs and securing the kill.

Recommended Builds and Party Setup

To make your run as smooth as possible, your team should utilize highly defensive sigils alongside damage-boosting masteries. This table outlines the optimal setup recommended by veteran players:

Character Slot	Recommended Character	Key Sigils	Role / Strategy
Main DPS	Siegfried	Stout Heart, Dragon's Bane, Damage Cap V+	Maintains high defense while cycling Dragon's Bane Pulse buffs.
Support / Healer	Sandalfon	Aegis, Potion Hoarder, Autorevive	Keeps the party healthy and provides crucial revives during Smus.
Ranged DPS	Tweyen (Playable)	Damage Cap V+, Quick Cooldown	Deals safe, consistent damage from a distance to avoid ground hazards.
Utility / Buffer	Yodarha	Mirror Image, Cascade, Uplift	Provides party-wide invincibility buffs and builds the SBA gauge rapidly.

Endless Ragnarok Rewards

Defeating Seofon and Tweyen with an S+ rank rewards you with some of the most powerful endgame materials available in the expansion.

Damage Cap V+ Sigils: Essential for breaking past the endgame damage limits.
Potion Hoarder V+ Sigils: Grants extra healing potions, which are vital for surviving subsequent high-difficulty quests.
Eternals Mastery Materials: Used to unlock the brand-new mastery trees for your characters, significantly boosting their base stats.

Using this endless ragnarok seofon tweyen boss guide, you can easily coordinate with your team, manage the Inner Monster gauges, dodge the deadly Smus waves, and secure your S+ clear in under ten minutes!

Frequently Asked Questions

Do Seofon and Tweyen have separate health bars?

No. As detailed in this endless ragnarok seofon tweyen boss guide, Seofon and Tweyen share a single, unified health bar. Damage dealt to either boss reduces the same overall health pool, allowing you to switch targets freely depending on who is currently easier to hit.

How do I stop Tweyen's Inner Monster state?

While it is extremely difficult to prevent her from entering the Inner Monster state initially, you can shorten its duration. By maintaining high DPS and attacking Tweyen while she is empowered, you will rapidly deplete her Inner Monster gauge and force her back into her normal, less aggressive state.

What happens if I fail the Star and Crown arrow trial?

If you fail to destroy all the arrow crystals before the central progress bar fills, or if any party member gets hit by the hazard zones during the trial, you will fail the "Wrath of Star and Crown" side goal. While you can still complete the quest, failing this goal prevents you from achieving an S+ rank and limits your endgame rewards.