Best Light Cone
Whereabouts Should Dreams Rest
Best Relic Set
Iron Cavalry 4pc
Planar Set
Forge of the Kalpagni Lantern
Key Mechanic
360% Break Effect
Best Partner
Ruan Mei / Fugue

Skills

Basic Flare Propulsion / Fyrefly Type-IV: Pyrogenic Decimation

In base form, deals Fire DMG equal to 50% of SAM's ATK to a single target. During Complete Combustion, this is enhanced to Fyrefly Type-IV: Pyrogenic Decimation. It restores HP equal to 20% of Max HP and deals Fire DMG equal to 100% of SAM's ATK to a single enemy. The enhanced version is SAM's primary source of toughness breaking during the combustion window.

100% enhanced ATK
Skill Order: Aerial Bombardment / Fyrefly Type-IV: Deathstar Overload

Base form consumes HP equal to 40% of Max HP and regenerates 50% of Max Energy, then deals Fire DMG equal to 100% ATK and advances Firefly's next action by 25%. Enhanced during Complete Combustion to Deathstar Overload: restores HP (25% Max HP), applies Fire Weakness to a single enemy for 2 turns, and deals Fire DMG equal to (0.2 × Break Effect + 100%) of ATK to that target, plus (0.1 × Break Effect + 50%) of ATK to adjacent targets. Break Effect in this calculation is capped at 360%.

172% at 360% BE cap
Ultimate Fyrefly Type-IV: Complete Combustion

Enters Complete Combustion, advances Firefly's action by 100%, and grants access to her Enhanced Basic ATK and Enhanced Skill. While in this state, increases SPD by +30, and each Enhanced attack increases Weakness Break efficiency by 50% and Break DMG dealt by 10% until that attack ends. A countdown timer (fixed SPD 70) appears on the Action Order. When the timer's turn arrives, SAM exits Complete Combustion. Firefly cannot use her Ultimate while inside Complete Combustion.

+30 SPD in state
Talent Chrysalid Pyronexus

Passive survivability engine. The lower Firefly's HP, the less DMG she receives. At 20% HP or lower, DMG Reduction reaches its maximum effect of 20%. During Complete Combustion, this maximum DMG Reduction is always active, and Effect RES increases by 10%. If her Energy is below 50% when battle starts, it is automatically restored to 50%. Once Energy reaches its maximum, all debuffs on Firefly are dispelled.

20% max DMG reduction
Technique Order: Meteoric Incineration

Leaps into the air and moves freely for 5 seconds, which can be ended early by launching a plunging attack. Upon landing, immediately attacks all enemies within a set area. At the start of each wave, applies Fire Weakness to all enemies for 2 turns, then deals Fire DMG equal to 200% of ATK to all enemies. A powerful opening tool that sets up Weakness Breaks across the entire enemy lineup before the first turn.

200% wave start AoE

Build Targets

Relic Main Stats
Head
HP (fixed)
Hands
ATK (fixed)
Body
ATK%
Feet
Speed
Planar Sphere
ATK%
Fire DMG% if well-rolled
Link Rope
Break Effect
Stat Targets
Break Effect360%+ (in combat)
ATK2600+
Speed150+ (154 w/ Ruan Mei)
Effect RES30%+
Substat Priority
01
Speed more turns in Combustion
02
Break Effect core damage stat
03
ATK% converts to BE via Module γ
04
Effect RES prevents CC
Skill Upgrade Order
Skill
1st
Ult
2nd
Talent
3rd
Basic
Skip
Skill first since Deathstar Overload is her primary damage source during Complete Combustion. Ultimate for more frequent combustion windows. Talent for passive survivability. Basic ATK is rarely used outside of combustion.

Best Light Cones

#1
Whereabouts Should Dreams Rest
Whereabouts Should Dreams Rest
Firefly's signature light cone. Provides a massive Break Effect bonus and converts excess Break Effect into DMG dealt by SAM. The best option by a clear margin at any investment level. Its passive directly amplifies every element of her kit.
signature
#2
On the Fall of an Aeon
On the Fall of an Aeon
Strong free-to-play alternative from the Herta Store. Provides stacking ATK% on attack and a DMG bonus when Weakness Breaking targets. Both effects synergize directly with Firefly's combat loop.
f2p best
#3
Something Irreplaceable
Something Irreplaceable
Solid 5-star alternative with an ATK bonus that scales further after defeating an enemy or taking a hit. Firefly's HP-draining Skill makes the defensive trigger easy to activate for the ATK boost.
alternative
#4
Indelible Promise
Indelible Promise
Provides Break Effect and a conditional ATK bonus on Weakness Break. Easy to superimpose and reliable. A good farmable option for players who don't have the 5-star alternatives.
4-star pick
#5
The Moles Welcome You
The Moles Welcome You
Budget option that stacks ATK% with each ability used. Since Firefly uses both Basic ATK and Skill during Complete Combustion, the ATK stacks build up quickly. Usable while saving for better options.
budget

Best Relics

Cavern Sets
1
Iron Cavalry Against the Scourge
Iron Cavalry Against the Scourge
Best-in-slot cavern set for Firefly. The 2-piece grants +16% Break Effect. The 4-piece allows Break DMG and Super Break DMG to ignore a portion of the target's DEF when Firefly's Break Effect reaches the required thresholds, both of which she easily achieves with her kit and proper supports. Nothing else competes on fully broken targets.
4-piece recommended
2
Thief of Shooting Meteor
Thief of Shooting Meteor (4pc)
Second-best option. Provides a large Break Effect bonus from both 2-piece and 4-piece bonuses, plus Energy regeneration whenever Firefly inflicts Weakness Break. Useful if you have better-rolled pieces in this set or don't yet have Iron Cavalry farmed.
4-piece
3
Thief of Shooting Meteor (2pc) + Messenger Traversing Hackerspace (2pc)
A mixed 2+2 option. Thief provides Break Effect and Messenger adds a Speed bonus. Viable if your specific relic pieces rolled excellent substats. Strictly inferior to a well-rolled 4-piece Iron Cavalry but workable while transitioning.
2+2 mix
Planar Ornament Sets
1
Forge of the Kalpagni Lantern
Forge of the Kalpagni Lantern
Best planar set for Firefly. Provides Speed via the 2-piece bonus plus an additional Break Effect increase when attacking enemies with Fire Weakness, which Firefly can apply herself. The combined stat package is unmatched for her Break-focused gameplay.
2-piece recommended
2
Talia: Kingdom of Banditry
Talia: Kingdom of Banditry
Alternative planar set providing Break Effect and a bonus Break Effect when Firefly's Speed is at 145 or higher, a threshold she comfortably meets with proper Speed investment and Complete Combustion's +30 SPD bonus. Solid backup option.
2-piece

Best Teams for Firefly

Firefly's Super Break DMG scales with Break Effect and toughness reduction. Her core synergy is with Harmony Trailblazer or Fugue who enable Super Break DMG for the entire team. Always pair with at least one Break Effect support.

01 · Premium Super Break Best-in-slot composition
Firefly
Firefly
Main DPS
Fugue
Break Support
Ruan Mei
Break / Harmony
Lingsha
Sustain
Fugue enables Super Break DMG for the team and provides additional toughness reduction. Ruan Mei amplifies Break efficiency and adds all-type RES PEN. Lingsha provides AoE healing while also increasing Break DMG received by enemies. The highest-ceiling composition available.
02 · Harmony Trailblazer Core Accessible F2P-friendly option
Firefly
Firefly
Main DPS
Trailblazer (Imaginary)
Break Support
Ruan Mei
Break / Harmony
Gallagher
Sustain
Harmony Trailblazer is the free-to-play core enabler for Super Break DMG, essential for Firefly. Ruan Mei provides Break Effect and the all-important toughness delay. Gallagher's healing scales with Break Effect and his Besotted debuff increases Break DMG taken.
03 · Fugue + Lingsha Break No Ruan Mei required
Firefly
Firefly
Main DPS
Fugue
Break Support
The Dahlia
Break Support
Lingsha
Sustain
The Dahlia replaces Ruan Mei, providing Break Effect and allowing Super Break DMG even against non-Weakness-Broken enemies while also increasing team Break Efficiency. Fugue and Lingsha further contribute Super Break DMG alongside Firefly for an impressive three-way break synergy.
04 · F2P Budget All accessible characters
Firefly
Firefly
Main DPS
Trailblazer (Imaginary)
Break Support
Asta
ATK / Speed
Gallagher
Sustain
For players without Ruan Mei or Fugue, Asta provides ATK and Speed buffs that benefit Firefly during Complete Combustion. Harmony Trailblazer remains non-negotiable as the Super Break enabler. Gallagher covers healing and Break amplification at no pull cost.
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Eidolons

E 1
In Reddened Chrysalis, I Once Rest
When using the Enhanced Skill, ignores 15% of the target's DEF. Additionally, the Enhanced Skill no longer consumes Skill Points. This massively frees up team Skill Points and the DEF ignore significantly boosts Super Break damage against high-DEF enemies. An excellent first eidolon well worth the extra pull.
High Pull Value
E 2
From Shattered Sky, I Free Fall
While in Complete Combustion, using the Enhanced Basic ATK or Enhanced Skill to defeat an enemy or to break their Weakness allows SAM to immediately gain 1 extra turn. This effect can trigger again after 1 turn. In multi-wave or multi-enemy encounters, this can generate a remarkable number of bonus actions, dramatically increasing DPS output.
Game Changer
E 3
Amidst Silenced Stars, I Deep Sleep
Skill Level +2 (up to max Lv. 15) and Basic ATK Level +1 (up to max Lv. 10). The Skill level increase is particularly valuable since Deathstar Overload is Firefly's primary damage source. A solid but not transformative upgrade on its own.
Solid Upgrade
E 4
Upon Lighted Fyrefly, I Soon Gaze
While in Complete Combustion, increases SAM's Effect RES by 50%. Combined with Chrysalid Pyronexus's passive 10% Effect RES bonus during combustion, Firefly becomes extremely resistant to crowd control effects when she needs it most, inside her crucial combat window.
Good Passive
E 5
From Undreamt Night, I Thence Shine
Ultimate Level +2 (up to max Lv. 15) and Talent Level +2 (up to max Lv. 15). The Ultimate level upgrade means more frequent Complete Combustion triggers, while the Talent upgrade improves her passive survivability. Incremental gains across important parts of her kit.
Incremental
E 6
In Finalized Morrow, I Full Bloom
While in Complete Combustion, increases SAM's Fire RES PEN by 20%. When using the Enhanced Basic ATK or Enhanced Skill, Weakness Break efficiency increases by an additional 50% (stacking with the base 50% from the Ultimate for 100% total). This effectively doubles the toughness reduction of every attack during Complete Combustion, enabling more frequent full Weakness Breaks.
Massive Upgrade

Major Traces

Module α: Antilag Outburst
Ascension 2
During Complete Combustion, attacking enemies that have no Fire Weakness can still reduce their Toughness, with the effect being equivalent to 55% of the original Toughness Reduction from abilities. This crucial trace means Firefly can break non-Fire Weakness enemies during her Ultimate window, dramatically expanding her usability across all content.
Module β: Autoreactive Armor
Ascension 4
When SAM is in Complete Combustion with a Break Effect at or above 200%/360%, attacking a Weakness-Broken enemy converts the Toughness Reduction of that attack into 1 instance of 35%/50% Super Break DMG. This is Firefly's signature damage multiplier and the reason 360% Break Effect is her non-negotiable stat goal.
Module γ: Core Overload
Ascension 6
For every 10 points of SAM's ATK that exceeds 1800, increases this unit's Break Effect by 0.8%. This trace creates a meaningful feedback loop between ATK and Break Effect. Reaching 2600 ATK provides roughly +64% additional Break Effect, making it significantly easier to hit and sustain the 360% threshold in combat.
+37.3%
Break Effect
+18%
Effect RES
+5
Speed

Upgrade Materials

Tatters of Thought
Character Ascension
Borisin Teeth
Trace Material
Raging Heart
Boss Drop
Lost Echo of the Shared Wish
Weekly Boss Drop

Frequently Asked Questions

No. Firefly performs well with On the Fall of an Aeon or Indelible Promise at lower investment levels. Her signature (Whereabouts Should Dreams Rest) is a meaningful upgrade but not required to clear all endgame content at E0. The most important thing is hitting the 360% Break Effect threshold through relics and team buffs.
Using her Ultimate activates Complete Combustion, which immediately advances Firefly's action by 100% and grants her Enhanced Basic ATK and Enhanced Skill. A countdown timer with a fixed SPD of 70 appears on the Action Order. When this timer's turn arrives, SAM exits Complete Combustion. During the state, she gets +30 SPD, maximum DMG Reduction from her Talent, and can break non-Fire Weakness enemies at 55% efficiency thanks to Module α. She cannot use her Ultimate again while in the state.
The key threshold is 360% Break Effect in combat, which is the cap for her Module β trace's Super Break DMG conversion (50% Super Break DMG per attack on Weakness-Broken enemies). You also want at least 2600 ATK so that Module γ converts the excess ATK into approximately +64% additional Break Effect. Break Effect from team buffs like Ruan Mei and Forge of the Kalpagni Lantern counts toward the threshold.
Yes, in two ways. First, her Enhanced Skill (Deathstar Overload) applies Fire Weakness to a single target for 2 turns. Second, Module α: Antilag Outburst lets all of her attacks during Complete Combustion reduce Toughness on non-Fire Weakness enemies at 55% efficiency. Her Technique also applies Fire Weakness to all enemies at the start of each wave. This makes her highly flexible across all enemy types in endgame content.
Aim for 150 SPD as a baseline. This gives enough turns before the Complete Combustion timer expires. With Ruan Mei on your team, target 154 base SPD (which becomes 164 with her buff), hitting the breakpoint for 3 attacks in the first cycle of endgame content. If using The Dahlia instead, aim for 178–188 SPD. The +30 SPD from Complete Combustion also applies during the state, so base Speed still matters for the turns you take outside of it.
E1 is excellent: it removes Skill Point consumption from the Enhanced Skill and ignores 15% DEF, both of which are high-value changes. E2 is a game-changer, granting extra turns on defeat or Weakness Break during Complete Combustion, massively increasing DPS in multi-enemy fights. E6 doubles toughness reduction efficiency during combustion and adds 20% Fire RES PEN. E3 and E5 are the typical level-up eidolons. E4 gives more Effect RES during combustion, strong for survivability but less direct DPS impact.
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