OUTERPLANE Core Fusion Eternal: Kit Upgrades and Build Guide

Unlocking Core Fusion for Eternal in OUTERPLANE adds a Burn debuff to her offensive attacks, transforming her from a situational debuffer into a hybrid sub-DPS. While her baseline form focuses on stripping buffs, breaking defense, and reducing enemy speed, the Core Fusion upgrade lets her generate continuous damage independent of target defense.

This upgrade is especially valuable against high-health Earth-element bosses such as Chimera in Gear Raid, where sustained damage-over-time (DoT) and armor reduction consistently speed up clear times.

How Core Fusion Changes Eternal

In her baseline kit, Eternal acts as a pure utility disrupter. Once she lands her initial defense and speed debuffs, her damage output drops significantly during skill cooldowns. Core Fusion addresses this downtime by applying Burn debuffs directly through her offensive skills.

Damage Over Time: Burn ticks at the start of an enemy's turn, bypassing defense to steadily deplete high-health boss pools.
Break Gauge Pressure: Adding sustained Burn effects helps accelerate boss break gauge depletion and maintains offensive pressure during defensive recovery turns.
Hybrid Utility: Eternal continues to apply defense reduction, speed reduction, and buff removal while contributing steady passive damage.

Feature	Baseline Eternal	Core Fusion Eternal
Primary Role	Utility Debuffer	Hybrid Debuffer & DoT Sub-DPS
Debuff Suite	Defense Down, Speed Down, Buff Strip	Defense Down, Speed Down, Buff Strip, Burn
Damage Source	Direct attacks (dependent on allies)	Direct attacks and passive Burn ticks
Boss Clear Role	Setup for primary damage dealers	Setup and continuous boss chip damage

Stat Priorities and Gear Sets

Core Fusion Eternal needs sufficient speed to apply debuffs before your primary damage dealers attack, along with enough Effectiveness to bypass boss resistance checks.

Stat Priorities

Speed: Act early to establish defense breaks and speed debuffs before enemies take action.
Effectiveness: Match or exceed the Effect Resistance thresholds of target raid bosses to ensure Burn and stat breaks land reliably.
Attack & Critical Hit Chance: Increase the baseline damage and scaling of her attacks and Burn effects.
Health & Defense: Provide baseline durability to survive boss area-of-effect abilities.

Recommended Gear Sets

Speed Set (4-Piece): The standard build. Minimizes turn delay so Eternal can cycle back to her debuff skills.
Hit Set (2-Piece): Pairs with the Speed Set to bridge the gap if substats do not meet boss resistance requirements.
Counter or Revenge Set (Alternative): Situational options for stall or reactive setups, giving Eternal extra chances to reapply Burn on enemy turns.

Team Compositions and Synergies

Core Fusion Eternal performs best in mono-Fire or debuff-heavy teams where her defense shredding and Burns amplify allied damage.

Turn Acceleration and Buffs (Valentine): Valentine grants team-wide Critical Hit Rate and Critical Damage buffs while providing turn priority, helping Eternal cycle her cooldowns faster.
Team Sustain (Astei): Astei provides healing and debuff immunity, keeping Eternal protected during extended PvE boss encounters.
Burst Damage Dealers (Rin or Demiurge Drakhan): Single-target Fire attackers capitalize directly on the defense debuffs Eternal applies, executing bosses while Burn ticks handle residual health.

Resource Investment Priority

Invest in Eternal's Core Fusion if your roster lacks a dedicated Earth-boss farming team or needs faster clear times in high-tier Gear Raids. Her hybrid kit fills both the defense-break and sub-DPS roles in a single team slot.

If you already have heavily invested mono-Fire lineups with dedicated burn specialists that clear Chimera without difficulty, her Core Fusion upgrade can remain a secondary priority.