Firefly is a Fire character on the Destruction path who turns Break Effect into raw damage. Her whole kit revolves around entering the Complete Combustion state, breaking enemy Weakness fast, and converting that into Super Break hits. Building her correctly means chasing Break Effect and Speed while keeping her attack high enough to satisfy her passive thresholds.
Quick answer: Run Iron Cavalry Against the Scourge (4-piece) with Forge of the Kalpagni Lantern (2-piece), main stats of ATK% body, Speed feet, ATK% planar sphere, and Break Effect link rope, then prioritize Speed and Break Effect substats. Pair it with a Break-focused light cone such as Whereabouts Should Dreams Rest.
Firefly best relics and ornaments
Iron Cavalry Against the Scourge is the primary relic set because Firefly deals a large share of her damage through Super Break, and this set boosts that output. If you cannot farm it yet, Genius of Brilliant Stars and Thief of Shooting Meteor are the fallback options. On the planar side, Forge of the Kalpagni Lantern is the standard pick, with Talia: Kingdom of Banditry as the alternative for extra Break Effect.
| Slot | First choice | Alternatives |
|---|---|---|
| Relic set (4-piece) | Iron Cavalry Against the Scourge | Genius of Brilliant Stars, Thief of Shooting Meteor |
| Planar ornament (2-piece) | Forge of the Kalpagni Lantern | Talia: Kingdom of Banditry |
Best main stats and substats
Firefly wants ATK% on the body and planar sphere to keep her attack above the thresholds her traces check, Speed on the feet to act more often, and Break Effect on the link rope to feed her Super Break scaling. For substats, Speed and Break Effect come first, followed by ATK%.
| Piece | Main stat |
|---|---|
| Body | ATK% |
| Feet | Speed |
| Planar Sphere | ATK% |
| Link Rope | Break Effect |
Substat priority runs Speed, then Break Effect, then ATK%, with any remaining rolls treated as flexible. Because her Ascension 6 trace grants Break Effect for every point of attack above 1800, hitting a high attack value directly improves her damage.
Best light cones for Firefly
Her signature light cone, Whereabouts Should Dreams Rest, is the strongest option because it leans into Break Effect and Break damage. Thus Burns the Dawn is a solid alternative, while On the Fall of an Aeon, Something Irreplaceable, and Indelible Promise cover more accessible choices.
| Tier | Light cone |
|---|---|
| Signature | Whereabouts Should Dreams Rest |
| Strong alternative | Thus Burns the Dawn |
| Accessible options | On the Fall of an Aeon, Something Irreplaceable, Indelible Promise |
How Firefly’s kit works
Firefly plays as SAM, and her abilities change depending on whether she is in the Complete Combustion state. Her Ultimate, Fyrefly Type-IV: Complete Combustion, advances her action by 100% and unlocks the Enhanced Basic ATK and Enhanced Skill. While combusting she gains 30 Speed, a 50% Weakness Break efficiency boost on enhanced attacks, and 10% increased Break damage against the target.
| Ability | What it does |
|---|---|
| Basic ATK — Order: Flare Propulsion | Deals Fire damage to one enemy; the enhanced version heals SAM and hits harder. |
| Skill — Order: Aerial Bombardment | Spends HP for Energy and deals Fire damage; the enhanced version applies Fire Weakness and scales with Break Effect. |
| Ultimate — Fyrefly Type-IV: Complete Combustion | Enters the combustion state and upgrades her Basic ATK and Skill. |
| Talent — Chrysalid Pyronexus | Reduces damage taken as HP drops and manages her Energy at battle start. |
| Technique — Order: Meteoric Incineration | Applies Fire Weakness to all enemies and deals area Fire damage before combat. |
Note: SAM cannot cast her Ultimate again while already in Complete Combustion, since a countdown timer with a fixed Speed of 70 controls when the state ends. Plan her rotation around re-entering combustion as soon as the state expires.
Traces and Break Effect thresholds
Her three major traces reward stacking Break Effect. Autoreactive Armor converts Toughness Reduction into Super Break damage once her Break Effect reaches 200% or 360% while combusting. That 360% figure is the same cap her enhanced Skill uses for its Break Effect scaling, which makes it a meaningful target when tuning gear.
| Trace | Effect |
|---|---|
| Module α: Antilag Outburst (A2) | Lets her reduce Toughness on enemies without Fire Weakness during Complete Combustion. |
| Module β: Autoreactive Armor (A4) | Turns Toughness Reduction into Super Break damage at 200%/360% Break Effect. |
| Module γ: Core Overload (A6) | Grants 0.8% Break Effect for every 10 ATK above 1800. |
Fully leveled traces add Break Effect +37.3%, Effect RES +18%, and SPD +5 to her totals. Because attack feeds Break Effect through Core Overload, an ATK% build stays valuable even though her damage comes from Break.
Eidolon effects
| Eidolon | Effect |
|---|---|
| E1 | Enhanced Skill ignores 15% of the target’s DEF and costs no Skill Point. |
| E2 | Defeating or breaking an enemy with an enhanced attack grants an extra turn, retriggerable after 1 turn. |
| E3 | Skill +2 (max Lv. 15) and Basic ATK +1 (max Lv. 10). |
| E4 | Increases Effect RES by 50% during Complete Combustion. |
| E5 | Ultimate +2 (max Lv. 15) and Talent +2 (max Lv. 15). |
| E6 | Adds 20% Fire RES PEN in combustion and another 50% Weakness Break efficiency on enhanced attacks. |
Ascension upgrade materials
To take Firefly to her level cap you need Tatters of Thought, Borisin Teeth, Raging Heart, and Lost Echo of the Shared Wish. Gather these alongside the standard credits and experience materials before pushing her ascension and trace levels.
Put together, the build is straightforward to plan even if the substat grind takes time. Lock in the ATK%, Speed, and Break Effect main stats, aim for a high Break Effect value in combustion, and keep her attack elevated so Core Overload keeps feeding her scaling.
