Guide
How the kit works
When an Intro Skill is available, enter with Dissonance to deal Fusion DMG and gain Annoyance on hit. Cast Passionate Variation, then hit with Impromptu Show. Those hits build Annoyance, and Basic Attack hits restore extra Annoyance for 5 seconds after Passionate Variation.
At 100 Annoyance, Passionate Variation becomes Fury Fugue. Cast it to consume all Annoyance and deal Fusion DMG counted as Resonance Skill DMG. Harmonic Control increases Fury Fugue's damage by 25% for 8 seconds after Passionate Variation, so try to use it within that window.
Cast Violent Finale before switching to apply Burning Rhapsody. A Basic Attack hit from the active character fires one Marcato; a Heavy Attack hit fires two. Mortefi can launch one coordinated attack every 0.35 seconds. Rhythmic Vibrato increases the next Marcato's damage by 1.5% per Marcato hit, up to 50 stacks, and resets when Burning Rhapsody ends.
Switch with Rage Transposition when you are ready to give the next Resonator its 14-second Heavy Attack bonus. Switching that Resonator out ends the bonus early. If an enemy's Off-Tune Level is full, Mortefi can also use Tune Break: Pistols (tune_break).
Build and why
Use the five-piece Moonlit Clouds setup. Its listed two-piece bonus gives 10% Energy Regen, which suits Mortefi's reliance on his Liberation. The supplied data does not describe the five-piece effect, so do not count on a particular bonus from it here.
Static Mist is the first weapon choice. It gives 12.8% Energy Regen and, after Mortefi uses his Outro Skill, increases the incoming Resonator's ATK by 10% for 14 seconds. That gives the character receiving his Heavy Attack bonus another benefit.
The Last Dance is the next option. It gives 12% ATK and raises Resonance Skill DMG Bonus by 48% for 5 seconds after an Intro Skill or Resonance Liberation. Fury Fugue counts as Resonance Skill DMG, so it can make use of that bonus. Cadenza follows: casting a Resonance Skill restores 8 Concerto Energy, once every 20 seconds.
Relativistic Jet is another option if you lack those weapons. Casting a Resonance Skill restores 6 Resonance Energy and gives 10% ATK for 16 seconds, once every 20 seconds. Energy Regen is a reasonable stat to look for, though no full stat distribution is provided.
Leveling priority
As a suggested order, level Violent Finale first because its coordinated attacks continue while another character is active. Follow it with Fury Fugue and Passionate Variation, which you use during Mortefi's time on the field. Dissonance (intro) and Impromptu Show can come afterward.
For maximum ascension, you need 170,000 Shell Credit, 4 LF Whisperin Core, 12 MF Whisperin Core, 12 HF Whisperin Core, 4 FF Whisperin Core, 46 Rage Tacet Core and 60 Coriolus.
To level all skills to the maximum, you need 2,030,000 Shell Credit, 25 LF Whisperin Core, 28 MF Whisperin Core, 40 HF Whisperin Core, 57 FF Whisperin Core, 26 Monument Bell, 25 Impure Phlogiston, 28 Extracted Phlogiston, 55 Refined Phlogiston and 67 Flawless Phlogiston. These skill costs are separate from ascension costs.
Resonance Chain nodes worth it
For a suggested Resonance Chain order, consider Cathartic Waltz (sequence 4) first. It extends Burning Rhapsody by 7 seconds, giving the active character more time to trigger Mortefi's coordinated attacks.
Apoplectic Instrumental (sequence 6) is another useful team upgrade: casting Violent Finale increases every team member's ATK by 20% for 20 seconds. Hypocritical Hymn (sequence 2) is worth considering for energy; using an Echo Skill restores 10 extra Resonance Energy once every 20 seconds.
You can leave Solitary Etude (sequence 1), Flaming Recitativo (sequence 3) and Funerary Quartet (sequence 5) for later if those other effects matter more to you. They add Marcato triggers or improve Marcato's Crit. DMG, but none is required for the basic switch-and-support plan.
Teams
Choose a field character you want to attack with after Mortefi switches out. Heavy Attack hits fire two Marcato and benefit from Rage Transposition, while Basic Attack hits fire one Marcato. Keep the recipient on the field if you want to use the full 14 seconds of the Outro bonus.
Jiyan and Augusta are teammate options named in the guide evidence. Verina is another listed option for a team slot. For example, you can try Mortefi with Jiyan and Verina, then direct the Outro bonus to the character whose Heavy Attacks you plan to use.
Mortefi's listed kit does not require a particular partner element. Pick the rest of the team around the character you want on the field rather than assuming a Fusion partner is required.
Common mistakes
Do not switch away from the recipient of Rage Transposition early if you still need its Heavy Attack bonus. The effect lasts up to 14 seconds, but ends as soon as that character leaves the field.
Do not overlook the timing after Passionate Variation. Basic Attack hits restore extra Annoyance for 5 seconds, while Harmonic Control gives Fury Fugue its damage increase for 8 seconds. Reaching 100 Annoyance lets you use the upgraded skill.
Do not confuse the energy provided by weapon effects. Cadenza restores Concerto Energy, while Relativistic Jet restores Resonance Energy. Also, the listed Moonlit Clouds data only describes its two-piece effect; it does not give a five-piece effect to plan around.
