Guide
How the kit works
Before a fight, use Posterior Precedence to gain Ward for 20 seconds. Entering combat while Ward is active casts Intuit: Cull on a random enemy, with that attack's damage increased by 80%.
On Yunli's turn, Bladeborne Quake restores HP equal to 30% of her ATK plus 200. It deals 120% of her ATK as Physical DMG to the target and 60% to adjacent enemies. Galespin Summersault instead deals 100% of her ATK to one target.
When an enemy attacks Yunli, Flashforge gives her 15 Energy and counters for 120% of her ATK against the attacker and 60% against adjacent targets. If there is no immediate target, the counter hits a random enemy. Using a counter also increases her ATK by 30% for one turn.
Use Earthbind, Etherbreak before an enemy turn when you expect Yunli to be attacked. It costs 120 Energy and grants Parry until the end of the next ally or enemy turn. The next counter gains 100% CRIT DMG. During Parry, Yunli resists Crowd Control debuffs and takes 20% less damage.
A counter during Parry becomes Intuit: Cull: it deals 220% of her ATK to the target, 110% to adjacent enemies, then six hits of 72% each to random enemies. If no counter triggers, Parry ends with Intuit: Slash, which has the same initial damage but no extra hits. After each Slash, the next Slash is replaced by Cull. Damage from these attacks counts as Ultimate DMG.
Build and why
Use four pieces of The Wind-Soaring Valorous. It gives 12% ATK and 6% CRIT Rate; after a Follow-Up ATK, it increases Ultimate DMG by 36% for one turn. Yunli's Ultimate counters count as Ultimate DMG, making that bonus useful for her kit.
For planar ornaments, Inert Salsotto gives 8% CRIT Rate and, at 50% CRIT Rate, 15% more Ultimate and Follow-Up ATK damage. Duran, Dynasty of Running Wolves is another option: its stacks increase Follow-Up ATK damage, and five stacks also give 25% CRIT DMG.
Dance at Sunset is the first weapon choice. It greatly increases Yunli's chance of being attacked, gives 36% CRIT DMG and grants Follow-Up ATK damage stacks after her Ultimate. The Unreachable Side gives 18% CRIT Rate and 18% Max HP; being attacked or consuming HP raises damage by 24% until the wearer attacks. On the Fall of an Aeon builds ATK stacks when Yunli attacks and gives a damage bonus after she breaks an enemy's Weakness.
Choose CRIT Rate or CRIT DMG on the body, ATK Percentage on the feet, Physical DMG Boost or ATK Percentage on the sphere, and ATK Percentage or Energy Regeneration Rate on the rope. For substats, favor CRIT Rate, CRIT DMG and ATK Percentage, then SPD. Balance the two CRIT stats rather than ignoring one.
Leveling priority
Level Earthbind, Etherbreak first because its counters are a major source of damage. Follow with Bladeborne Quake for its damage and self-healing, then Flashforge for the regular counter. Leave Galespin Summersault until last.
For maximum ascension, gather 308,000 Credit, 65 IPC Work Permit, and 15 each of Artifex's Module, Artifex's Cogwheel and Artifex's Gyreheart.
Maxing all skills takes 3,000,000 Credit, 8 Tracks of Destiny, 18 Borisin Teeth, 69 Lupitoxin Sawteeth, 139 Moon Rage Fang, 12 Regret of Infinite Ochema, 41 Artifex's Module, 56 Artifex's Cogwheel and 58 Artifex's Gyreheart. These skill costs are separate from ascension.
Eidolons worth it
Walk in Blade, Talk in Zither is a strong late upgrade to consider. During Parry, an enemy actively using an ability triggers Intuit: Cull even if it does not attack Yunli. Slash and Cull also gain 15% CRIT Rate and 20% Physical RES PEN.
Weathered Blade Does Not Sully is a useful early stopping point: it raises Slash and Cull damage by 20% and adds three extra damage instances to Cull. First Luster Breaks Dawn is another option, letting counter damage ignore 20% of the target's DEF.
If you stop earlier, consider leaving E3 through E5 aside. E3 and E5 raise skill levels, while E4 gives Effect RES after Slash or Cull. Yunli can still use her counter kit without any Eidolons.
Teams
Give Yunli a sustain teammate because she wants to take enemy attacks. Huohuo is a Wind sustain option, while Lynx is a Quantum alternative. Yunli's own healing helps her recover HP, but it does not heal the rest of the team.
Tingyun is a Lightning buffer named in several guides. Tribbie is a Quantum buffer with a Follow-Up role, making her worth considering alongside Yunli and a Follow-Up-focused planar set. Sunday is another buffer option.
For a fourth slot, consider Pela as an Ice debuffer or another damage dealer such as Herta, who has an Ice Follow-Up role. The team does not need one fixed element beside Yunli: choose the remaining slots around survival and support for her damage.
Common mistakes
Do not use Earthbind, Etherbreak without checking whose turn comes next. Parry ends after that turn, so an ally acting first can leave Yunli with Intuit: Slash instead of an enemy-triggered Cull. An enemy also needs to attack Yunli to trigger the counter during Parry before E6.
Do not treat a missed Cull as a wasted Ultimate every time. After a Slash, the next Slash is replaced by Cull. Still, timing Parry for an incoming attack lets you aim for Cull now rather than relying on that later replacement.
Do not neglect CRIT Rate while stacking CRIT DMG. Inert Salsotto also needs 50% CRIT Rate for its damage bonus. Finally, remember that Yunli's self-heal only restores her own HP, so the team still needs a way to stay alive.