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Last updated: 15/September/2026
Best guide and build for Cartethyia from WW (Wuthering Waves). Cartethyia is a 5★ rarity character from the 
Aero element who uses the Sword type weapon.
Cartethyia has at least one video guide available:
Last review update
Patch 3.6
Last major build/calcs update
Patch 3.6
Last profile update*
15/September/2026
*Profile update means smaller edits to echoes, stats, synergies or teams that don't require new calculations.
To learn more about Cartethyia check the sections below. Use the tabs to quickly switch to the kind of information you're looking for.
Profile
Sword to Carve My Forms
Basic Attack - Cartethyia
Perform up to 4 consecutive attacks, dealing Aero DMG.
Following Basic Attack - Cartethyia Stage 4, inflict 1 stack of Aero Erosion on targets hit and summon Sword of Divinity's Shadow.
Up to 1 Sword of Divinity's Shadow may exist at the same time, lasting for 20s.
Heavy Attack - Cartethyia
Consume STA to attack the target, dealing Aero DMG and summoning Sword of Discord's Shadow. Can be performed in mid-air.
Up to 1 Sword of Discord's Shadow may exist at the same time, lasting for 20s.
This instance of DMG is considered Basic Attack DMG.
Mid-air Attack - Cartethyia
Release Normal Attack button while airborne to perform Plunging Attack at the cost of STA, dealing Aero DMG, also considered Aero Erosion DMG.
Press Normal Attack shortly after the Plunging Attack to perform Basic Attack - Cartethyia Stage 2.
Casting Mid-air Attack - Cartethyia recalls all Sword Shadows. Based on the types and number of Sword Shadows recalled, perform different forms of Plunging Attack and obtain the corresponding Heart of Virtue, Mandate of Divinity, and Power of Discord.
Dodge Counter - Cartethyia
Press Normal Attack shortly after a successful Dodge to attack the target, dealing Aero DMG.
Sword to Bear Their Names
Resonance Skill - Cartethyia
Attack the target, launch nearby enemies, and then plunge them to the ground, dealing Aero DMG and inflicting 2 stacks of Aero Erosion on the targets hit. This instance of DMG is considered Basic Attack DMG. Can be performed in mid-air.
Following Cartethyia - Resonance Skill, summon Sword of Virtue's Shadow.
Up to 1 Sword of Virtue's Shadow may exist at the same time, lasting for 20s.
A Knight's Heartfelt Prayers
Resonance Liberation - A Knight's Heartfelt Prayers
By reducing HP to 50% of the Max HP, Cartethyia transforms into Fleurdelys, unlocking new moves and entering the Manifest state for 12s.
Can be performed in mid-air.
Entering Manifest clears all Conviction.
As Fleurdelys, Basic Attack - Fleurdelys Stage 5, Mid-air Attack - Fleurdelys Stage 2, and Resonance Skill - May Tempest Break the Tides instantly trigger 1 instance of Aero Erosion DMG and reduce the Aero Erosion stack on the target hit by 1.
Ending the state will not clear Resonance Energy.
No HP cost when HP is below 50%.
Fleurdelys's attacks restore Conviction on hit. When Conviction reaches 120 points, press Resonance Liberation to cast Resonance Liberation - Blade of Howling Squall.
When Conviction is below 120 points, press Resonance Liberation to transform back into Cartethyia. When in Manifest, casting Resonance Liberation - A Knight's Heartfelt Prayers as Cartethyia consumes no Resonance Energy.
When Fleurdelys has Heart of Virtue in Manifest:
Basic Attack - Fleurdelys Stage 4 will generate a force field to Stagnate the targets within the range.
Fleurdelys's resistance to interruption increases.
Heart of Virtue is removed when Manifest ends.
When Fleurdelys has Mandate of Divinity in Manifest:
Aero Erosion DMG is Amplified by 50% and the damage interval is decreased by 50% for enemies within a certain distance from Fleurdelys.
Mandate of Divinity is removed when Manifest ends.
When Fleurdelys has Power of Discord in Manifest:
When casting Basic Attack - Fleurdelys Stage 5, Mid-air Attack - Fleurdelys Stage 2 and Enhanced Heavy Attack - Fleurdelys or after Resonance Skill - May Tempest Break the Tides deals damage, raise the Aero Erosion stacks on all nearby targets to the highest count among the targets.
Power of Discord is removed when Manifest ends.
Fleurdelys will transform back to Cartethyia during quest dialogues, environmental interaction animations, or using Utilities.
Fleurdelys can walk on water. Doing so on deep waters continuously consumes STA. When in walking state, Fleurdelys can step out of a high place and walk in mid-air by continuously consuming STA.
Avatar - Cartethyia
As Fleurdelys, when Conviction is below 120 points, press Resonance Liberation to perform Basic Attack - Cartethyia Stage 2 and temporarily transform back to Cartethyia, which pauses the timer on Manifest.
Can be cast in mid-air. Casting the skill in mid-air performs Mid-air Attack - Cartethyia.
Avatar - Fleurdelys
When in Manifest, casting Resonance Liberation as Cartethyia performs Basic Attack - Fleurdelys Stage 2 without consuming Resonance Energy and transforms her back to Fleurdelys, which resumes the timer on Manifest.
Can be cast in mid-air. Casting this skill in mid-air performs Mid-air Attack - Fleurdelys Stage 1.
Resonance Liberation - Blade of Howling Squall
When Fleurdelys has 120 points of Conviction, Resonance Liberation - A Knight's Heartfelt Prayers is replaced by Resonance Liberation - Blade of Howling Squall.
Casting Resonance Liberation - Blade of Howling Squall removes all Conviction, ends Manifest, restores 50% of Max HP, and then deals Aero DMG to all targets in an area along a straight line in front. Upon hitting the target, remove all stacks of Aero Erosion on the target. Each stack removed Amplifies the DMG taken by the targets by 20%, up to 5 stacks.
Can be cast in mid-air.
Tempest
Cartethyia unlocks new moves when she transforms into Fleurdelys:
Basic Attack - Fleurdelys
Basic Attack - Cartethyia is replaced by Basic Attack - Fleurdelys.
Perform up to 5 consecutive attacks, dealing Aero DMG and restoring Conviction on hit.
Mid-air Attack - Fleurdelys
Mid-air Attack - Cartethyia is replaced by Mid-air Attack - Fleurdelys.
Perform up to 3 consecutive attacks in the air at the cost of STA, dealing Aero DMG and restoring Conviction on hit.
While airborne, hold Normal Attack to cast Mid-air Attack - Fleurdelys Stage 3.
Follow up with Basic Attack shortly afterward to cast Basic Attack - Fleurdelys Stage 3.
While airborne, casting Resonance Skill - Sword to Answer Waves' Call and Resonance Skill - May Tempest Break the Tides resets the cycle of Mid-air Attack - Fleurdelys.
Heavy Attack - Fleurdelys
Heavy Attack - Cartethyia is replaced by Heavy Attack - Fleurdelys.
Thrust forward to deliver a focused strike, dealing Aero DMG and restoring Conviction on hit. This instance of DMG is considered Basic Attack DMG.
Enhanced Heavy Attack - Fleurdelys
While casting Heavy Attack - Fleurdelys, press Normal Attack again to cast Enhanced Heavy Attack - Fleurdelys: fall back and blast the area in a straight line in front, dealing Aero DMG and restoring Conviction on hit. This instance of DMG is considered Basic Attack DMG.
Follow up with Basic Attack shortly after casting Enhanced Heavy Attack - Fleurdelys to cast Upward Cut - Fleurdelys.
Upward Cut - Fleurdelys
While Fleurdelys is on the ground, Jump to cast this skill, dealing Aero DMG and restoring Conviction on hit.
Dodge Counter - Fleurdelys
Dodge Counter - Cartethyia is replaced by Dodge Counter - Fleurdelys.
Press Normal Attack shortly after a successful Dodge to attack the target, dealing Aero DMG and restoring Conviction on hit.
Follow up with Basic Attack shortly afterward to cast Basic Attack - Fleurdelys Stage 4 .
Resonance Skill - Sword to Answer Waves' Call
Resonance Skill - Cartethyia is replaced by Resonance Skill - Sword to Answer Waves' Call.
Summon a force field near the target's location to continuously pull in nearby targets, dealing Aero DMG and restoring Conviction on hit.
Can be cast in mid-air.
Resonance Skill - May Tempest Break the Tides
Following Resonance Skill - Sword to Answer Waves' Call, press Resonance Skill again to call down a giant Sword Shadow to crush an area around the target, creating a force field to pull in nearby targets, dealing Aero DMG to ground targets, and restoring Conviction on hit.
Follow up with Basic Attack shortly afterward to cast Basic Attack - Fleurdelys Stage 3.
The Resonance Skill enters cooldown if Resonance Skill - May Tempest Break the Tides is not cast within a certain period or when switching to another Resonator.
Can be cast in mid-air.
A Heart's Truest Wishes
The healing received by all Resonators other than Cartethyia/Fleurdelys in the team is increased by 20% and their resistance to interruption is enhanced. If Rover: Aero is in the team, Rover: Aero additionally restores 25 Windstrings upon casting Omega Storm.
Wind's Indelible Imprint
Targets with 1 to 3 stacks of Aero Erosion take 30% more DMG from Cartethyia and Fleurdelys. Targets with more than 3 stacks of Aero Erosion additionally take 10% more DMG from Cartethyia and Fleurdelys for each stack of Aero Erosion they have, up to 3 stacks.
Sword to Mark Tide's Trace
Cartethyia - Sword to Mark Tide's Trace
Deal Aero DMG and inflict 2 stacks of Aero Erosion on targets hit. Summon Sword of Discord's Shadow.
Up to 1 Sword of Discord's Shadow may exist at the same time, lasting 20s.
Press Normal Attack shortly after Cartethyia - Sword to Mark Tide's Trace to perform Basic Attack - Cartethyia Stage 2.
Fleurdelys - Sword to Call for Freedom
Thrust forward to impale the target, dealing Aero DMG and restoring Conviction.
Press Normal Attack shortly after Fleurdelys - Sword to Call for Freedom to cast Basic Attack - Fleurdelys Stage 2.
Wind's Divine Blessing
Aero DMG dealt by the active Resonator in the team other than Cartethyia/Fleurdelys to targets with Negative Statuses is Amplified by 17.5% for 20s.
Sequence Node 1
Gain Zeal that lasts for 10s when Cartethyia's or Fleurdelys's attacks directly damage and defeat targets inflicted with Aero Erosion.
In the Zeal state, upon defeating enemies, the next move that directly damages targets raises the Aero Erosion stacks on the targets to the highest count among the targets defeated. This will not exceed the current max Aero Erosion stack limit. Zeal is removed afterward and enters a 1s cooldown.
When Fleurdelys's Conviction hits 30/60/90/120, Fleurdelys's Crit. DMG is increased by 25% for 15s, up to 4 stacks. The duration of this effect does not reset upon gaining new stacks. After casting Resonance Liberation - Blade of Howling Squall, the increased Crit. DMG is removed.
Sequence Node 2
Casting Resonance Liberation - A Knight's Heartfelt Prayers increases the max stack limit of Aero Erosion on targets within a certain range by 3 stacks. The next attack that directly damages the target inflicts 3 stacks of Aero Erosion on all targets within a certain range and immediately triggers the Aero Erosion DMG on the targets hit once without consuming the Aero Erosion stacks.
The DMG Multipliers of Cartethyia's Basic Attack, Heavy Attack, Dodge Counter, and Intro Skill are increased by 50% and the DMG Multiplier of her Mid-air Attack is increased by 200%.
After casting Mid-air Attack - Cartethyia, every 1 type of Sword Shadow recalled reduces the cooldown of Resonance Skill - Cartethyia by 1s.
Sequence Node 3
Basic Attack - Fleurdelys Stage 5, Mid-air Attack - Fleurdelys Stage 2, Enhanced Heavy Attack - Fleurdelys, and Resonance Skill - May Tempest Break the Tides now inflict 2 stacks of Aero Erosion on the targets hit.
The DMG Multiplier of Resonance Liberation - Blade of Howling Squall is increased by 100%.
Sequence Node 4
After Resonators in the team inflict Havoc Bane, Fusion Burst, Spectro Frazzle, Electro Flare, Glacio Chafe, or Aero Erosion, all Resonators in the team gain 20% DMG Bonus for all Attributes for 20s.
Sequence Node 5
When Cartethyia or Fleurdelys takes a fatal blow, they will not be downed by this instance of damage, but instead gain a Shield equal to 20% of Cartethyia's Max HP for 10s. This effect can be triggered once every 10 min.
The HP cost for casting Resonance Liberation - A Knight's Heartfelt Prayers is reduced to 25% of Max HP.
Sequence Node 6
After casting Resonance Liberation - Blade of Howling Squall, raise the Aero Erosion stacks on the target hit to max. Casting Resonance Liberation - Blade of Howling Squall no longer removes the Aero Erosion stacks on the target.
Within 30s after casting Intro Skill - Sword to Mark Tide's Trace, Intro Skill - Sword to Call for Freedom, Resonance Liberation - A Knight's Heartfelt Prayers, and Resonance Liberation - Blade of Howling Squall, when any Resonator in the team inflicts Aero Erosion on the targets with max stacks of Aero Erosion, immediately trigger the Aero Erosion DMG once.
The targets take 40% more DMG from Fleurdelys.
CRIT Rate
HP%HP
ATK
DEF
Max EnergyCRIT Rate
CRIT DMG
Healing Bonus
Aero DMGWhile the source of the materials can be quickly found in the game, when it comes Bamboo Iris you will have to gather them from the map. Check our Interactive map to find them quickly:
Review
Please keep in mind Wuthering Waves is a skill-based game and each character has a different playstyle, difficulty level and even special tricks and combos. Wuthering Waves is also a team based game and it's only by combining both these factors to the highest level a character can reach optimal performance.
Self-sufficient: heals herself, applies and amplifies Aero Erosion, making her able to exploit her kit by herself (albeit not to its fullest potential);
Massive room for optimization through quickswap - none of her teammates have any issues when it comes to utilizing the mechanic to its fullest potential, meaning her ceiling is much higher than her baseline performance;
High sequence scaling, particularly her S2 and S3 offer great benefits that alleviate her otherwise somewhat strict teambuilding conditions;
Possesses interruption resistance, grouping and stagnating, Increases teammate interruption resistance & healing, funnels Forte points to Aero Rover if present — makes team rotations much smoother;
INSANE second Ultimate animation.
HP scaling means alternative weapon options to her Signature really fall behind. Overall one of the most Signature weapon-reliant characters in the game;
In multi-wave content, non-negotiably requires her ideal teammate Ciaccona in order to function correctly - not even ideal in gamemodes like Whimpering Wastes, but to use her there Ciaccona is not skippable;
Requires a lot of optimization in her rotations to function without Ciaccona in any gamemode in general, Ciaccona being a character who is very difficult to acquire nowadays due to a lack of reruns.
Cartethyia is a 5-star Aero Sword DPS character who relies on the Aero Erosion mechanic to take her damage to the next level. Defined by a very Quickswap-friendly kit and a very flexible rotation with many tools at her disposal, breaking her kit down requires some much needed simplification. We’ll try to provide as concise and clear of an explanation as we can throughout this review.Key Mechanics
Something to note to start with, is that the entirety of Cartethyia’s damage is based on her HP. This makes building her certainly original, but also way more restrictive, as most Swords and Echo sets revolve around buffing ATK. This makes her a very selective DPS in general and is one of her main flaws - but we’re getting ahead of ourselves, so let’s start with her kit in the order of her rotation:
First of all, Cartethyia has two forms. Her Ultimate allows her to transform into Fleurdelys to gain a new kit, but before that, she needs to accumulate what’s known as “Sword Shadows”. There are 3 types of Sword Shadows, all of which enhance her kit in her Fleurdelys form where she will deal the overwhelming majority of her damage. All Sword Shadows acquired are visible on her Forte bar in her Cartethyia form. Their effects to Fleurdelys are as follows:
Sword of Discord: Gained after using Cartethyia’s Intro Skill or Heavy Attack, it raises the Aero Erosion stacks on all nearby enemies to whatever count is highest among the currently remaining enemies after using most of Fleurdelys’s important abilities. This has two effects: the first is keeping all enemies in range at the same amount of Aero Erosion, the second is refreshing the duration of Aero Erosion (so the stacks will never expire mid-rotation). However, it’s worth noting this does not help her in multi-wave content;
Sword of Divinity: Gained after using Cartethyia’s Basic Attack 4, it amplifies Aero Erosion DMG by 50% and reduces the damage interval by 50% for enemies near Fleurdelys (meaning the damage is applied twice as fast effectively doubling the damage on top of 50% Amplification);
Sword of Virtue: Gained after using Cartethyia’s Skill, it allows her to gain increased Interruption Resistance and generate a stagnation field after using her Basic Attack 4 in Fleurdelys form.
Another effect stacking up each Sword will have is enhancing Cartethyia’s Mid-Air Attack. Using this Mid-Air Attack summons all Sword Shadows to attack the enemy, inflicting high damage and granting their effects to Fleurdelys. Hence, it is mandatory to cast this Mid-Air Attack every rotation to ensure Fleurdelys is as buffed as can be to deal the highest amount of damage possible. Besides, the damage on this ability is high, so increasing it further isn’t a bad idea in any context.
Cartethyia’s Intro Skill and Resonance Skill each apply 2 stacks of Aero Erosion on the targets hit, while Basic Attack 4 applies 1 stack, for a total of 5 Aero Erosion stacks per rotation. The limit is naturally 3 stacks, however this can be increased via Aero Rover or Chisa’s Outro skills and via Cartethyia’s Sequence 2 (each increasing the limit by 3). At most, Fleurdelys benefits from 6 Aero Erosion stacks being present on her targets. Via Cartethyia’s Inherent Skill, all damage dealt by Cartethyia and Fleurdelys on targets affected by Aero Erosion increases by 30% regardless of their stack count. For every stack above 3, she also gains an extra 10% Aero Erosion up to 30% at 6 stacks (for a total of 60% DMG Bonus). This gives her a tremendous amount of DMG Bonus, further adding on to the necessity to apply Aero Erosion on her targets.
Aero Erosion will periodically deal some decent damage to your enemies throughout your team’s rotation, and will also be directly consumed by Cartethyia once she transforms into Fleurdelys to enhance her attacks.
Upon using her Ultimate, Cartethyia transforms into Fleurdelys. This makes her gain the “Manifest” state which grants the following effects:
When transforming into Fleurdelys, Cartethyia immediately reduces her Max HP to 50% of its original value (unless her current HP is already equal to or below 50%). The Manifest state lasts for 12s.
Fleurdelys gains a brand new kit with new Basic Attacks, 2 new Heavy Attacks, 2 new Resonance Skills, a new Forte bar called “Conviction” which allows her to cast her second Ultimate (the hardest-hitting ability she has), a brand new Intro Skill and certain attacks make her consume Aero Erosion instead of applying it.
When using several key abilities, Fleurdelys will consume 1 stack of Aero Erosion to instantly deal the instance of damage it normally would’ve done.
When using any ability, Fleurdelys restores a portion of Conviction, stackable up to 120. At 120 points, she is able to cast her second Ultimate, deal massive damage in this process, and end her rotation.
The damage of this second Ultimate is influenced by how much Aero Erosion is present on the targets, up to 5 stacks. Each of these 5 potential stacks get removed on cast and amplify the damage of the attack by 20% each (up to 100%).
The second Ultimate restores 50% of Cartethyia’s (not Fleurdelys’s) max HP.
Lastly, her Outro amplifies Aero DMG dealt to targets with Negative Status applied by 17.5% for 20s by allies other than herself, which is an acceptable boost but nothing impressive.
All of Cartethyia’s kit mechanics tied to Aero Erosion consumption aren’t utilizable to their fullest on her own. She lacks enough Aero Erosion application to do so before S3, and before S2 she cannot naturally increase the stack cap of Aero Erosion on the targets. This makes someone who has that ability, either Chisa or Aero Rover, ideal. She will need to slow her rotation down, or be paired with extra sources of Aero Erosion application (ideally Ciaccona) to take full advantage of her kit.
At S0, Cartethyia’s teams do get restricted by the nature of her kit’s mechanics, as they tie her down to specific Aero Erosion teammates. However, even without Ciaccona available, considering Aero Rover is a free character who can increase the stack cap of Aero Erosion on targets, Cartethyia does get fantastic damage on her own, as her kit is mostly self-sufficient. Add that to an insane affinity for Quickswap (more than basically any other character in the game), and overall you are left with a pretty complete character, although her damage ceiling is expectedly not up to the standard of her most modern DPS peers. However, using her fullest quickswap potential, she can get very close, and that’s a testament to her affinity for the mechanic.
In conclusion, Cartethyia is a good all-around damage dealer to this day. Her affinity for quickswap provides her a long standing in the upcoming meta for people who wish to optimize her to the fullest. In the hands of the average person, she remains a decent choice for a DPS, particularly if her Sequence nodes are unlocked, although she wouldn’t be a recommended pull for new players today. Having inevitably fallen behind the most modern DPS characters of Wuthering Waves, Cartethyia nonetheless remains a capable damage dealer who can provide some good results under the right conditions, and some amazing results in the right quickswappy hands.
Build
The percentages show the performance of the weapon based on calculations, but in some cases, some weapons might provide additional QOL that can't be quantified and it would push that weapon ahead of others in the priority (and in those cases, we would put that weapon higher).
Cartethyia calculations were done using added buffs from the following teammates:
Ciaccona + Woodland Aria + 
Gusts of Welkin
Rover (Aero) + Bloodpact's Pledge + 
Windward Pilgrimage
100.00%
79.50%
76.30%
77.00%
75.90%
75.70%
72.30%
100.00%
Best set for Aero Main DPS characters who can apply Aero Erosion or have an Aero Erosion applier on the team. Grants 10% Aero DMG Bonus and an extra 30% Aero DMG Bonus as well as 10% CRIT Rate for 10s when attacking targets inflicted with Aero Erosion. Offers an extra 10% CRIT Rate over the other Aero sets such as Gusts of Welkin or Sierra Gale, providing extra overall damage so long as Aero Erosion is present on the enemy.
Below you can find Main Echo options:
Substats: Energy Regen (Until Satisfied) > CRIT Rate = CRIT DMG > HP% > Basic Attack DMG% = Liberation DMG% > HP
All recommended endgame stats portray a fairly good quality endgame build as a goal to aim for on most characters. However, don’t treat this as an end-all-be-all, and more of a suggestion.
All stat recommendations are given at S0 for 5-stars, S6 for 4-stars, and free characters (unless specified otherwise), based on total stats in the in-game stat-screen with the character out of combat but also active in the party (and hence some buffs may or may not apply). Any other precision may be directly specified. If not specified, Energy Regen requirements are estimated in the character’s best team.
HP: 35000-50000+
DEF: 600+
CRIT Rate: 65-80%+
CRIT DMG: 240-270%+
Energy Regen: 110%+
Aero DMG Bonus: 30%+
Below you can find the order of leveling the abilities for Cartethyia.
Forte Circuit
Res. Liberation
Basic Attack
Res. Skill
Intro Skill
Skill and Intro can be skipped when levelling to save on resources at a minimal damage loss.
Gameplay and teams
Cartethyia wants to build up 3 Sword Shadows and plunge in her base form before dealing the majority of her damage in Fleurdelys form.
Summon Reminiscence: Fleurdelys at any point in her rotations. It may be used to temporarily slow down enemies as it has this effect.
This rotation provides the best mix of damage relative to amount of time spent without any quickswap when performed correctly.
Intro - Cartethyia
Basic 2 - Cartethyia
Basic 3 - Cartethyia
Basic 4 - Cartethyia (Cancel animation endlag via Skill)
Skill - Cartethyia
Basic: Mid-air Attack - Cartethyia (Cancel when she hits the ground via Ultimate)
Ultimate (Transform to Fleurdelys)
Skill - Fleurdelys 1
Heavy - Mid-Air Attack 3 - Fleurdelys
Basic 3 - Fleurdelys
Basic 4 - Fleurdelys
Basic 5 - Fleurdelys (Cancel animation endlag via Skill)
Skill: Fleurdelys 2
Basic 3 - Fleurdelys
Basic 4 - Fleurdelys
Basic 5 - Fleurdelys (Cancel animation endlag via Ultimate)
Ultimate: Blade of Howling Squall
(OPTIONAL) Heavy: Cartethyia (Swap)
Outro
The rotation below is used in teams with low Aero Erosion generation to preserve
Fleurdelys damage. (Any team that isn't with Ciaccona, or Chisa + Aerover).
This works because cancelling Fleurdelys’s Basic Attack 5 with either of her Ultimates in time preserves the attacks’ full damage, but doesn't consume Aero Erosion.
Intro - Cartethyia
Skill - Cartethyia
Basic: Mid-air Attack - Cartethyia (Cancel when she hits the ground via Ultimate)
Ultimate (Transform to Fleurdelys)
Skill - Fleurdelys 1
Skill - Fleurdelys 2
Basic 3 - Fleurdelys
Basic 4 - Fleurdelys
Basic 5 - Fleurdelys (Cancel animation endlag via Ultimate)
Ultimate (Transform to Cartethyia)
Basic 2 - Cartethyia
Basic 3 - Cartethyia
Basic 4 - Cartethyia (Cancel animation endlag via Ultimate)
Ultimate (Transform to Fleurdelys)
Basic 2 - Fleurdelys
Basic 3 - Fleurdelys
Basic 4 - Fleurdelys
Basic 5 - Fleurdelys (Cancel animation endlag via Ultimate)
Ultimate: Blade of Howling Squall
Basic 1 - Cartethyia
Basic 2 - Cartethyia
Basic 3 - Cartethyia
Basic 4 - Cartethyia (Cancel animation endlag via Heavy)
Heavy - Cartethyia (Swap)
Outro
The final Basic Attack chain after Fleurdelys’s Ultimate is necessary in order
to have all 3 Swords before the next Intro without Outro buffs expiring on Fleurdelys, and also make use of Cartethyia's Outro / Windward Pilgrimage on Aero Rover.
The final Heavy Attack is performed solely because it's free extra damage.
During the Opener rotation, perform the final Cartethyia Basic 1234 + Heavy first in your team.
The listed animation cancels used in the rotations above occur as follows
Cartethyia Basic 4: As soon as it is cast
Fleurdelys Basic 5: When she drops her sword on enemies (sword starts falling from the sky)
Cartethyia Mid-air Attack: When Cartethyia lands
Cartethyia Basic 4 —> Heavy: It’s possible to hold Heavy on the same input as Basic 4.
In Quickswap, Cartethyia has many good swap cancel windows. In Cartethyia form, her Basic 3, 4, Skill, and Mid-air Attack all have their niche use cases. In Fleurdelys form, her Skill 2 and Basic 4/5 are the main ones used. Her best team is fully quickswap-friendly, so many team-specific quickswap combos are possible.
Ciaccona - The best Sub DPS option for Cartethyia, who has a short rotation whilst doing great damage, provides good buffs via her Solo Concert, Echo set and potential weapon, and amplifies Aero Erosion damage by 100% on Outro. But most importantly, Ciaccona applies a ton of Aero Erosion off-field over time, which allows Cartethyia to make full leverage of her kit buffs. For these reasons, they are best when paired together.Rover (Aero) 
Chisa 
The Shorekeeper - All of the three best third slot Support choices Cartethyia has. While Ciaccona is consistently on all of her best teams, each of these characters have their use cases. Aero Rover and Chisa are built to make full leverage of Cartethyia's kit since they can each increase the Aero Erosion stack count on enemies by 3; Shorekeeper is mostly used in Whimpering Wastes since ramping Aero Erosion up to 6 is difficult in multi-wave content so her buffs and rotation speed can see use. While Chisa has better buffs than Aero Rover, that's only with her Signature weapon equipped. Pick and choose your support based on your situation, and you can always play 2 of them as an alternative if Ciaccona isn't available!
Sanhua - Sanhua works with Cartethyia as her best F2P pair, because buffing Basic Attack DMG for her isn't too bad as it buffs a number of her abilities, but most importantly Sanhua rotates in and out at lightspeed, while still being able to provide some buffing via her Echo set. As she doesn't apply any Aero Erosion, Sanhua's main purpose is mostly to get in and get out for Cartethyia to take all available field time. For these reasons, it's an acceptable duo, still stronger than alternatives like Aalto as he doesn't back up his field time with enough damage and barely gives any higher buffing potential.Team #1
Chisa is only stronger than Aero Rover with her Signature. Shorekeeper is also mostly usable in the third slot in Whimpering Wastes since Aero Erosion won't have time to ramp up to 6.
Team #2: Alternative Teams
Remember Aero Rover is the 2nd character in the rotation with Chisa or Shorekeeper on the team, but they open the rotation with Sanhua on the team. Also use Skyfall Severance to convert Havoc Bane into Erosion if you use them with Chisa!
Calculations