Si is a 6-star Cryo Operator in Arknights: Endfield who can deal strong damage while supporting the entire team. Her Ultimate provides Cryo and Heat Amp, and her unique Talent reduces the Combo Skill cooldown of the Operator in the first team position. This makes her a useful choice for teams that depend on frequent Combo Skills and Arts Infliction.
In this guide, we will go through Si’s best builds, weapons, gear sets, skill priorities, and how to use her properly. If you have recently obtained Si or want to improve her performance in endgame content, choosing the right equipment and team setup will make a big difference.
I recommend building Si primarily as a sub-DPS with strong support capabilities. Her damage improves when enemies have multiple Infliction stacks, while her Ultimate helps increase the damage of Cryo and Heat teammates. Let’s look at her best build and the alternatives you can use if you don’t have her top weapon.
Arknights Endfield Si Best Builds and Weapons Guide
Character Detail
Information
Rarity
6-Star
Element
Cryo
Weapon
Greatsword
Class
Supporter
Main Attribute
Intellect
Secondary Attribute
Strength
Faction
Hongshan Academy of Sciences
How to Get
Rejuvenation Headhunt
Si is not just a regular support. She has a mix of damage, crowd control, team buffs, and Combo Skill cooldown reduction. Her Battle Skill applies Infliction and creates an opportunity to deal additional damage through Artful Intent.
Her Combo Skill deals Cryo damage based on the highest number of Arts Infliction stacks consumed or absorbed from a single target. Her Ultimate then deals Cryo damage and grants Cryo Amp and Heat Amp to the team.
What Makes Si Good?
Strong team support: Her Ultimate increases Cryo and Heat damage through Amp.
Good sub-DPS damage: Her Combo Skill scales with the Infliction stacks consumed or absorbed.
Combo Skill cooldown reduction: Her Proxy’s Patronage Talent reduces the Combo Skill cooldown of the Operator in the first team position.
Crowd control: Her Battle Skill can immobilize enemies.
Flexible team options: She can support both Cryo and Heat teams, depending on your team setup.
Her main strength comes from combining personal damage with team utility. However, to get the most out of her, you need to build her around Intellect, Combo Skill damage, and enough Ultimate Efficiency to maintain her buffs.
Si Best Build
Si performs best as a sub-DPS who can also provide powerful support. For an endgame build, I recommend using Jade Vessel with the Type 50 Yinglung gear set and Redeemer Seal as the off-piece.
Best Si Build Summary
Equipment Slot
Best Choice
Weapon
Jade Vessel
Armor
Type 50 Yinglung Soft Armor
Gloves
Type 50 Yinglung Gloves
Kit I
Type 50 Yinglung Beacon
Kit II
Redeemer Seal
Main Stat Priority
Efficacy
Secondary Priorities
Intellect Boost, Cryo DMG Boost
This setup improves Si’s damage through Intellect, Strength, and Combo Skill DMG bonuses. Jade Vessel also provides useful supporting effects, while Redeemer Seal helps with Ultimate uptime.
Best Stats for Si
When selecting equipment and weapon Essences, prioritize the following:
Efficacy: A priority for her recommended weapon setup.
Intellect Boost: Improves her primary attribute.
Cryo DMG Boost: Increases her Cryo damage output.
Combo Skill DMG: Helps improve the damage of her main offensive Combo Skill.
Ultimate Efficiency: Useful for keeping her team-wide Amp buffs available more consistently.
You do not need to focus entirely on damage. Si’s value also comes from her Ultimate and cooldown-reduction Talent, so maintaining a reliable rotation is important.
Si Best Weapons Ranked
Jade Vessel is Si’s best overall weapon because it supports both her personal damage and her team’s damage output. However, there are other options worth considering if you have not obtained it.
Rank
Weapon
Best Essence Priorities
1
Jade Vessel
Efficacy, Intellect Boost, Cryo DMG Boost
2
Khravengger
Attack Boost, Detonate, Strength Boost
3
Long Heritage
Efficacy, Intellect Boost, Cryo DMG Boost
4
Exemplar
Attack Boost, Main Attribute Boost, Suppression
1. Jade Vessel — Best Overall
Jade Vessel is the weapon I recommend for Si if you want to maximize her overall performance. It increases her damage through Intellect, Cryo DMG, Combo Skill DMG, and Attack-related benefits.
Its Efficacy effect also helps improve her supporting capabilities by increasing the damage enemies take. This makes it a better all-around option than a weapon that only improves her personal damage.
For the recommended endgame build, use Jade Vessel with Type 50 Yinglung gear and Redeemer Seal.
2. Khravengger — Strong Damage Alternative
Khravengger is a good alternative when you want to focus more on Si’s personal damage. Its Attack and Strength-related bonuses can help her deal more damage.
The main drawback is that it does not provide the same supporting benefits as Jade Vessel or Long Heritage. Its Detonate effect can also be less consistent in practice because Si’s Combo Skill usually triggers after Inflictions have already been consumed.
Use Khravengger if it is your strongest available option, but Jade Vessel remains the more complete choice.
3. Long Heritage — Good Alternative
Long Heritage is worth considering if you have the Battle Pass weapon available. Its stats are similar to Jade Vessel, making it a practical alternative for Si.
Its Efficacy effect improves Si’s Cryo damage when she uses her Battle Skill. Casting her Ultimate also allows the weapon to provide a team Arts DMG Dealt buff.
This makes Long Heritage a useful choice when you want Si to contribute both damage and support without relying on Jade Vessel.
4. Exemplar — Budget Option
Exemplar is a fallback option if you do not have the weapons above. Its Attack and Main Attribute bonuses can still provide useful stats.
However, Si does not benefit from its Suppression effect because she is a Cryo character who does not deal Physical DMG. Treat Exemplar as a stat-focused alternative rather than her ideal weapon.
Si Best Gear and Gear Sets
Si has two main gear options: Type 50 Yinglung for a damage-focused sub-DPS build and Eternal Xiranite for a more team-oriented support build.
Best Gear: Type 50 Yinglung
Recommended pieces:
Type 50 Yinglung Soft Armor
Type 50 Yinglung Gloves
Type 50 Yinglung Beacon
Redeemer Seal
The Type 50 Yinglung set provides ATK +15%. When an Operator on the team casts a Battle Skill, the wearer gains a stack of Yinglung’s Edge, increasing the damage of their next Combo Skill by 20%. This effect can stack up to three times.
This is Si’s recommended endgame setup because it improves her personal damage while allowing her to contribute meaningful damage through her Combo Skill.
It is particularly useful in Cryo teams with characters such as Yvonne and Last Rite, who can consume multiple Cryo Infliction stacks and help Si reach higher Combo Skill damage.
Why Use Redeemer Seal?
Redeemer Seal is recommended as the off-piece because it provides Intellect and Ultimate Efficiency. These stats help Si maintain her Ultimate buffs more reliably.
Cryo teams can generate frequent SP returns, especially when using Operators such as Tangtang and Last Rite. Depending on the team rotation, this can affect how quickly Si gains the resources she needs for her Ultimate.
If your main goal is to maximize Si’s personal damage rather than improve her Ultimate uptime, you can consider LYNX Slab instead.
Alternative Gear: Eternal Xiranite
For a more support-focused setup, use:
Eternal Xiranite MOD Armor
Eternal Xiranite Channeling Gloves
Eternal Xiranite Rangefinder
Redeemer Seal
The Eternal Xiranite set provides HP +1000. More importantly, after the wearer applies Amp, Protected, Susceptibility, or Weakened, other teammates gain 16% DMG Dealt for 15 seconds. This effect cannot stack.
This is a useful alternative when no other Operator on your team is already using the set. For example, if Arcane or Ardelia is not equipped with Eternal Xiranite, Si can use it to contribute another team damage buff.
You can still use LYNX Slab instead of Redeemer Seal if you want to prioritize Si’s own damage.
Which Gear Set Should You Choose?
Type 50 Yinglung: Choose this for a damage-focused sub-DPS Si.
Eternal Xiranite: Choose this when you want to improve team damage and no other teammate is using the set.
Redeemer Seal: A good choice when you need more Ultimate Efficiency.
LYNX Slab: Consider it when you want to focus more heavily on Si’s personal damage.
For most players building Si as a sub-DPS, Type 50 Yinglung is the starting point I recommend.
How to Play Si
Si works best when you coordinate her Battle Skill, Combo Skill, and Ultimate with the rest of your team. Instead of treating her as a character who only deals damage, use her abilities to prepare enemies, increase team damage, and improve the timing of your main damage dealer’s Combo Skill.
1. Apply Cryo or Heat Infliction With Her Battle Skill
Si’s Battle Skill, Brushwork Realm, applies Artful Intent and Immobilization to the target. It also applies Cryo Infliction or Heat Infliction depending on the element of the Operator in the first team position.
If the first-position Operator is a Heat character, Si applies Heat Infliction. Otherwise, she applies Cryo Infliction.
Artful Intent records part of the damage dealt to the target. When its duration ends, it bursts and deals Fixed DMG based on the recorded damage. This damage ignores the target’s DEF, RES, and DMG Reduction effects.
The Immobilization effect also briefly stops enemies, giving your team an opportunity to continue attacking.
2. Use Initial Stroke to Pull an Inksoul
After Brushwork Realm, Si’s Battle Skill temporarily changes to Initial Stroke. This allows her to pull an Inksoul from a target affected by Artful Intent.
Damage and effects applied to the Inksoul are shared with its host. This creates another way for Si and her teammates to affect the linked target.
If the host is defeated while the Inksoul is still active, the Inksoul can link to another enemy in combat. You can also use Final Stroke to make the Inksoul disappear early and trigger the burst damage.
Timing matters here. Try to use the skill while there is enough time remaining on Artful Intent to make the effect worthwhile.
3. Trigger Her Combo Skill After Infliction Is Consumed
Si’s Combo Skill, Fully Envisioned, summons an Ink Lung that deals Cryo damage. It triggers when an enemy’s Cryo or Heat Infliction is consumed or absorbed.
Its damage depends on the highest number of Arts Infliction stacks consumed or absorbed from a single target. The Combo Skill itself does not consume those stacks.
This is why Si works well with teammates who consume several Infliction stacks in one rotation. Build up the stacks, coordinate your team’s attacks, and let Si’s Combo Skill contribute additional damage after the trigger condition is met.
4. Use Her Ultimate to Buff the Team
Si’s Ultimate, No One Spoils the Fun, summons a Giant Ink Lung that deals Cryo damage and grants temporary Cryo Amp and Heat Amp to the entire team.
Her Proxy’s Patronage Talent also reduces the Combo Skill cooldown of the Operator in the first team position after she casts her Ultimate.
For the best results, use her Ultimate when your main damage dealer is ready to take advantage of the Amp buffs and cooldown reduction. This helps you get more value from both her support effects and your team’s damage rotation.
Si Skill Priority
For a general sub-DPS and support build, prioritize Si’s Ultimate and Combo Skill first.
Priority
Skill
Reason
1
Ultimate
Improves her team-wide Cryo and Heat Amp buffs.
2
Combo Skill
Increases the damage of one of her main offensive abilities.
3
Battle Skill
Improves Artful Intent’s damage conversion.
4
Basic Attack
Lower priority for her usual support and sub-DPS role.
Talent Priority
Priority
Talent
Reason
1
Proxy’s Patronage
Improves her core support effect by reducing the first-position Operator’s Combo Skill cooldown.
2
Unsoiled Brush
Grants Haste to allied Operators when the Inksoul disappears.
Proxy’s Patronage is especially important because it adds utility that goes beyond Si’s personal damage. Unsoiled Brush is also useful, but it should generally come after your main skills and core Talent investment.
If you plan to control Si on the field frequently and rely on her Finisher Attacks, you can consider investing more in Basic Attack later. For her standard support and sub-DPS role, however, it remains the lowest priority.
Si’s Best Talents and Abilities
Si has two Talents that improve her team’s performance.
Proxy’s Patronage
This Talent reduces the Combo Skill cooldown of the Operator in Team Position 01 after Si casts her Ultimate.
Level 1: Reduces the cooldown by 10 seconds.
Level 2: Reduces the cooldown by 20 seconds.
This is one of Si’s defining support effects. To benefit from it, make sure the Operator you want to support is placed in the first team position.
Unsoiled Brush
When Si’s Inksoul disappears, allied Operators gain Haste for five seconds.
Level 1: Grants 15% Haste.
Level 2: Grants 30% Haste.
This Talent gives the team a short window of increased speed. Use it as part of your rotation rather than treating it as a separate damage ability.
Si Potentials: Are They Worth It?
Si’s Potential upgrades improve her damage, support effects, and Ultimate performance. However, you should not feel forced to obtain duplicates just to make her usable.
Potential
Effect
P1 — Spring and Autumn as Ink
Increases Immobilization duration, Artful Intent’s damage record ratio, and burst radius.
P2 — Three Marks Deep in Wood
Grants an ATK buff after her Combo Skill based on the highest Arts Infliction stacks consumed or absorbed.
P3 — Study of Muscles and Bones
Increases Ultimate damage and the strength of its Amp effect.
P4 — Perfectly Composed in Spirit
Reduces Ultimate Energy cost by 15%.
P5 — Brush Dab in Eye’s White
Reduces Combo Skill cooldown by two seconds, increases its damage, and counts one additional Infliction stack when triggered.
Best Potentials to Consider
P2 improves Si’s personal damage through its temporary ATK buff, while P3 improves both her Ultimate damage and Amp effect. P4 helps with Ultimate availability, and P5 is a substantial upgrade to her Combo Skill.
These upgrades are useful, but the value you get from each one depends on how often you use Si and which team you run. If you are saving resources, I would prioritize getting her weapon and core gear in place before chasing multiple duplicates.
Si Upgrade Materials
If you plan to level Si and upgrade her abilities, prepare the following materials.
Promotion Materials
Material
Total Required
Pink Bolete
3
Red Bolete
5
Ruby Bolete
5
Cosmagaric
8
Protodisk
33
Protoset
60
Warp Plasma-Coated Slide
20
T-Creds
152,200
Skill Materials
Material
Total Required
Kalkodendra
12
Chrysodendra
16
Vitrodendra
16
False Aggela
84
Protoprism
328
Protohedron
472
D96 Steel Sample 4
116
T-Creds
688,800
Talent Materials
Material
Total Required
Protoprism
133
Protohedron
90
T-Creds
98,400
These are the totals listed for Si’s promotion, skill, and Talent upgrades. Check your current inventory before farming so you can focus on the materials you are actually missing.
Best Teams for Si
Si can support both Cryo and Heat teams, so your team composition should determine which parts of her kit you focus on.
Cryo Teams
Si works well with Cryo damage dealers such as Yvonne and Last Rite. These characters can consume multiple Cryo Infliction stacks, helping Si’s Combo Skill deal more damage.
Tangtang can also be a useful teammate in Cryo compositions, particularly when the team’s resource generation and rotation support Si’s Ultimate.
Heat Teams
Si can also support Heat compositions by providing Heat Amp through her Ultimate. Her Battle Skill can apply Heat Infliction when a Heat Operator occupies the first team position.
This makes her worth considering if you want a support who can contribute damage while improving the team’s Arts damage output. The exact team should depend on which Heat Operators you own and how reliably they can trigger their abilities.
Team-Building Tips
Place your main Combo Skill damage dealer in the first team position to benefit from Proxy’s Patronage.
Use teammates who can consume multiple Infliction stacks to improve Si’s Combo Skill damage.
Time her Ultimate around your team’s major damage window.
Avoid duplicating Eternal Xiranite if another teammate already provides the set’s effect.
Use Redeemer Seal if Ultimate uptime is a problem; consider LYNX Slab for a more damage-focused setup.
Si is a flexible 6-star Cryo Supporter who can deal respectable damage while providing valuable buffs and cooldown reduction. Her strongest role is generally as a sub-DPS, but she can also contribute as a support in Cryo and Heat teams.
For the recommended endgame setup, use Jade Vessel, Type 50 Yinglung gear, and Redeemer Seal. If you want to emphasize team damage instead, consider Eternal Xiranite when no other teammate is already using it.
Focus on her Ultimate first, followed by her Combo Skill and Battle Skill. Most importantly, build your team around Infliction consumption and place the Operator you want to support in the first team position. With the right rotation and equipment, Si can contribute both meaningful damage and strong team utility.
