Guide
How the kit works
Start in Threshold State. Use the team's Echo Skills while Galbrena is in that state: each differently named Echo gives her 8 Afterflame, up to 40. Repeating an Echo with the same name won't add more until the effect resets when she leaves Demon Hypostasis. Her own attacks and Intro Skill build Sinflame on hit.
At 100 Sinflame, Edge Transcended becomes Ascent of Malice. Cast it to enter Demon Hypostasis and turn Sinflame into Purging Flame. Each point of Afterflame increases the damage of the listed enhanced attacks by 1.5%, up to 60%. The state ends when Purging Flame runs out or after more than 50 seconds; Afterflame and Sinflame are removed when she exits.
Use Hellfire Absolution during Demon Hypostasis for its 85% DMG Multiplier increase on the listed enhanced attacks for 14 seconds. It deals Echo Skill DMG itself. Follow it with a Normal Attack to start the enhanced Basic Attack at stage 2. After Ascent of Malice, you can also go straight to that stage.
Beyond Threshold gives Galbrena Hellstride: press Dodge on the ground while casting her skills to deal fixed Fusion DMG without resetting her attack cycle for a short time. It can trigger a successful Dodge, but cannot be used consecutively. Oathbound Hunt rewards hits from different skill types with Fated End stacks, each amplifying her listed direct damage by 5% for 5.5 seconds, up to four stacks.
Build and why
Use the recommended three-piece Flamewing's Shadow setup. The set's effects aren't specified here, so there is no detailed set bonus to plan around. For stats, ATK and Heavy Attack DMG Bonus are good options because Galbrena's kit repeatedly deals that damage type.
Lux & Umbra is the first weapon to look at. It gives 12% ATK, then rewards Echo Skill DMG with 24% Heavy Attack DMG Amplification for 6 seconds and Heavy Attack DMG with 24% Echo Skill DMG Amplification for 6 seconds. With both effects active, damage ignores 8% of the target's DEF. Her attack chains have hits of both types.
Phasic Homogenizer is another option: it gives 12% ATK and grants its wielder 20% All-Attribute DMG Bonus for 14 seconds after a teammate casts Tune Break. The Last Dance also gives 12% ATK, plus Resonance Skill DMG Bonus after Intro Skill or Resonance Liberation. Check damage classifications rather than assuming every hit from a Resonance Skill counts as Resonance Skill DMG.
Static Mist is an alternative with Energy Regen and an ATK increase for the incoming Resonator after Galbrena's Outro Skill. For a 4-star choice, Solar Flame builds ATK and Heavy Attack DMG Bonus stacks from Basic Attack or Heavy Attack DMG.
Leveling priority
As a starting order, level Beyond Threshold first for the enhanced state, then Hellfire Absolution for its damage and its contribution to that window. Next, consider Slayer's Trigger, Edge Transcended, and Hellflare Overload. This is a suggested order rather than a fixed requirement.
For maximum ascension, collect 46 Blighted Crown of Puppet King, 60 Stone Rose and the four tiers of Tidal Residuum: 4 LF Tidal Residuum, 12 MF Tidal Residuum, 12 HF Tidal Residuum and 4 FF Tidal Residuum. Ascension also costs 170,000 Shell Credit.
For all skills, you need 2,030,000 Shell Credit and 26 Curse of the Abyss. The other materials are 25 LF Tidal Residuum, 28 MF Tidal Residuum, 40 HF Tidal Residuum, 57 FF Tidal Residuum, 25 Impure Phlogiston, 28 Extracted Phlogiston, 55 Refined Phlogiston and 67 Flawless Phlogiston.
Resonance Chain nodes worth it
For the largest upgrades, I'd look at sequence 6, then sequence 1 and sequence 2. I Remain Who I am, Eternal My Flame (sequence 6) changes Demon Hypostasis into Eternal Hypostasis, retaining its effects while adding DMG Multiplier to several enhanced attacks. It also grants up to 35% Fusion DMG Amplification to the listed moves based on Afterflame when Ascent of Malice is cast.
Heart of Defiance Ever Ablaze (sequence 1) gives the listed enhanced moves 2% Crit. DMG per point of Afterflame, up to 80%. It also makes enhanced Basic Attack stage 5, enhanced Heavy Attack stage 3 and the enhanced Mid-air Attack immune to interruption. Hellbound Dive of Fire and Abyss (sequence 2) increases the ATK Bonus from Burning Drive by 350%.
Sequences 3 through 5 are options rather than necessities if you want to stop after sequence 2. Sequence 3 increases Resonance Liberation's DMG Multiplier, sequence 4 gives the team an all-Attribute DMG Bonus when a team member casts an Echo Skill, and sequence 5 increases the DMG Multipliers of the listed Resonance Skills.
Teams
Give Galbrena teammates who can use differently named Echo Skills while she is in Threshold State. Each new name adds Afterflame, which raises the damage of her enhanced moves in Demon Hypostasis. Reusing the same Echo name doesn't keep building that resource.
Brant, Iuno, Mortefi and Changli are other named options. Galbrena supplies on-field Fusion damage, and Ashen Pursuit deals Fusion DMG when she switches out. Her sequence 4 can also give the team an all-Attribute DMG Bonus after a team member casts Echo Skill.
Common mistakes
Don't enter Demon Hypostasis automatically as soon as Sinflame is full if you still need to use teammates' Echo Skills for Afterflame. Build that resource in Threshold State first, and remember that duplicate Echo names only count once before the reset.
Don't treat every Normal Attack as Basic Attack DMG. Slayer's Trigger classifies its first three Basic Attack stages as Heavy Attack DMG and stage 4 as Echo Skill DMG. The enhanced chain also changes classification for its later hits, so read weapon effects against the actual damage type.
Watch STA when using aerial attacks or Heavy Attacks. Sin Feaster restores 10 STA after certain final attack stages, but an interrupted aerial barrage cannot immediately be recast if Galbrena hasn't landed. Hellstride can help you dodge without resetting the attack cycle briefly, but you can't cast it consecutively.
