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Si Build Guide: Best Weapon, Gear & Teams | Arknights: Endfield
2026-10-23
Si is a 6-star Cryo Supporter from Arknights: Endfield Version 1.6 who hits hard while making the rest of the team hit harder. Her Combo Skill deals the majority of her personal damage and scales off Yinglung's Edge stacks earned through teammates' Battle Skills. She can work in both Cryo and Heat compositions with the right team-building rule. This Arknights: Endfield Si build guide covers her best weapons, gear sets, stat priorities, teams, skills, and more.
Si Character Overview
 | Rarity | 6-star |
| Class | Supporter | |
| Element | Cryo | |
| Weapon | Greatsword |
Si is a 6-star Cryo Supporter in Arknights: Endfield who scales with Intellect and Strength. She brings a mix of team buffs and strong Combo Skill damage, with much of her gameplay revolving around Artful Intent and Inksoul. Artful Intent stores a portion of the damage enemies receive before releasing it, while Inksoul creates a stationary target that redirects attacks and effects to the linked enemy.
The defining mechanic of Si build in Arknights: Endfield is her interaction with the first team slot. If a Heat operator occupies that position, her Battle Skill applies Heat Infliction instead of Cryo. Her Ultimate also elevates Cryo and Heat damage, so she is useful in either team composition.
Si can also reduce the first operator's Combo Skill cooldown through Proxy's Patronage. This makes team positioning important, as choosing who occupies Slot 1 determines how well Si supports the team's damage rotation.
Si Skills and Kit
Basic Attack – Artistic Urge
Arknights Si build performs up to five Greatsword attacks that deal Cryo damage. Her final Basic Attack also contributes Stagger when she is the controlled operator. Against Staggered enemies, she can perform a powerful Finisher that restores some SP.
Battle Skill – Brushwork Realm
Brushwork Realm deals Cryo damage and applies Immobilization alongside Artful Intent and an elemental Infliction.
Artful Intent remains on the enemy for 20 seconds, recording a portion of the damage it receives. Once the effect ends, the accumulated damage is released as AoE Fixed DMG. After the initial cast, Si gains access to two follow-up actions:
- Initial Stroke: Creates an Inksoul linked to the marked target for 15 SP. Attacks and effects directed at the Inksoul are passed to the original enemy.
- Final Stroke: Removes the Inksoul early and triggers the stored-damage explosion without additional SP.
Inksoul is useful against mobile bosses because it gives your team a stationary target. However, striking the Inksoul and its host with the same attack does not double the damage.
Combo Skill – Fully Envisioned
Si's best build summons an Ink Lung that deals Cryo damage when an enemy's Cryo or Heat Infliction is consumed or absorbed.
The damage increases with the number of Infliction stacks, which makes this her primary offensive ability. Teams that can reliably build and consume multiple stacks will get much more damage from her.
Ultimate – No One Spoils the Fun
Si summons a Giant Ink Lung that deals Cryo damage and grants the entire team Cryo Amp and Heat Amp for 12 seconds. The bonuses scale with skill level and reach 36% at maximum rank.
With Proxy's Patronage unlocked, casting her Ultimate also reduces the Combo Skill cooldown of the operator in Team Position 1 by 10 seconds, which increases to 20 seconds when the talent is upgraded.
Si Talents
- Proxy's Patronage: Reduces the first team member's Combo Skill cooldown after Si casts her Ultimate.
- Unsoiled Brush: Grants allied operators Haste when an Inksoul disappears. At maximum talent level, the bonus reaches 15%-30% Haste for 5 seconds.
Si Skill Priority
Combo Skill > Ultimate > Battle Skill > Basic Attack
Fully Envisioned (Combo Skill) deserves the most investment because its damage makes up a large part of Si's personal contribution. Upgrade her Ultimate next for stronger elemental amplification, followed by Brushwork Realm (Battle Skill). Basic Attacks are useful, but less important when she primarily supports another damage dealer. For a heavily support-oriented Endfield Si build, you can prioritize the Ultimate alongside the Combo Skill.
Si Upgrade Materials
The following table lists the Si materials needed for four Promotion stages, based on the current Endfield Hub progression data. EXP materials, skill upgrades, and other progression costs are not included.
| Material | Total |
 Protodisk | 33 |
 Protoset | 60 |
 Pink Bolete | 3 |
 Red Bolete | 5 |
 Ruby Bolete | 5 |
 Cosmagaric | 8 |
 Warp Plasma-Coated Slide | 20 |
 T-Creds | 126,100 |
Si Best Weapons
Signature Weapon - Jade Vessel
 | Rarity: 6-star Type: Greatsword Base ATK: 500 Intellect: +156 Cryo DMG Bonus: +43.33% Effect: Increases ATK by 25.6%. Applying Immobilization makes the target take 12% more damage for 30s. Applying Immobilization or casting an Ultimate also increases the wielder's next Combo Skill damage by 40% if used within 20s. |
Jade Vessel is Arknights: Endfield Si's best weapon because she can activate its benefits through her normal rotation. Brushwork Realm provides Immobilization, which enables the enemy damage-taken debuff, while the Combo Skill bonus strengthens her largest personal damage source. Since the debuff affects damage taken by the target, the rest of the team benefits as well.
Pro Tip: Planning to pull Si or her signature weapon? Check out Arknights: Endfield top-ups on BuffBuff for Origeometry packages to help prepare your pulls.
Alternative Si Weapons
1. Long Heritage
| - | Rarity: 6-starType: GreatswordBase ATK: 485 Intellect: +156Cryo DMG Bonus: +43.33%Effect: Increases the main attribute by 11.2%. Applying Cryo or Heat Infliction through a Battle Skill grants 9.6% Cryo DMG for 20s. Granting Arts Amp to another teammate increases the entire team's Arts DMG by 6.4% for 20s. |
Long Heritage is an accessible Si weapon alternative from the Version 1.6 Protocol Pass. Its Intellect and Cryo bonuses suit Si well, and its passive rewards the same elemental application she already performs in combat. It is a practical choice for players who want to save their pulls rather than chase Jade Vessel.
Khravengger
 | Rarity: 6-star Type: Greatsword Base ATK: 505 Strength: +156 ATK Bonus: +39% Effect: Increases all Skill DMG by 32%. Applying Cryo Infliction with a Battle Skill grants 16% Cryo DMG for 15s. Dealing Combo Skill damage to a Cryo-inflicted enemy provides another 32% Cryo DMG for 15s. |
Khravengger is a solid alternative for an Arknights Si weapon in Cryo teams, as it offers additional Skill DMG, ATK, and Cryo damage bonuses. However, its Strength stat is less valuable than Intellect, and its passive is harder to activate when Si applies Heat Infliction. It works best as a temporary option if you already own it.
Si Best Gear and Stat Priority
Type 50 Yinglung – Best Gear Set
| Set Bonus | Effect |
| 3-Piece | Increases ATK by 15%. Each team Battle Skill cast grants one stack of Yinglung's Edge, improving the wearer's next Combo Skill damage by 20% per stack, up to three stacks. |
Type 50 Yinglung is the Si best gear because her biggest damage contribution comes from Fully Envisioned. Teammates naturally activate the set while preparing elemental Inflictions, which allow Si to build up to a 60% Combo Skill damage bonus before her next Ink Lung attack.
Recommended gear pieces:
| Gear Slot | Recommended Piece |
| Armor |  Type 50 Yinglung Soft Armor |
| Gloves |  Eternal Xiranite Channeling Gloves |
| Kit 1 |  Type 50 Yinglung Beacon |
| Kit 2 |  Type 50 Yinglung Beacon |
This setup completes the three-piece Yinglung bonus while using Channeling Gloves for additional offensive stats. Another viable arrangement uses Type 50 Yinglung Gloves v2 and a Beacon, which frees the final Kit slot for LYNX Slab or Redeemer Seal.
Eternal Xiranite – Support Alternative
Eternal Xiranite is another recommended Si gear in Arknights: Endfield when Si's teammates benefit more from additional team damage than from her personal Combo Skill output.
Its three-piece effect increases other team members' damage after the wearer applies certain buffs, including Amp. Si can activate the bonus with her Ultimate, but the same set's team buff does not stack with another copy of the set.
If Xaihi or another teammate already wears Eternal Xiranite, Type 50 Yinglung is generally the better choice for Si.
Si Stat Priority
| Priority | Stats |
| Main Attribute | Intellect |
| Secondary Attribute | Strength |
| Offensive Bonus | Combo Skill DMG |
| Situational | Ultimate Gain Efficiency |
Focus on Intellect, Strength, and Combo Skill DMG when improving her offensive gear. Ultimate Gain Efficiency becomes more attractive when Si's main job is keeping her elemental Amp and cooldown support available for a dedicated carry.
Si Best Team Comps
Si performs best with teammates who can consistently apply and consume Cryo or Heat Inflictions. The first team position is especially important, so the lineups below are shown in their intended order.
Si Cryo Combo Team
 Si |  Tangtang |  Arcane |  Xaihi |
This Si team composition lets her take the first slot and benefit from her own cooldown reduction. Tangtang and Xaihi support Cryo application, while Arcane can consume stacks through Corrosion to trigger Fully Envisioned. It is one of the strongest starting points for a Si-centered team.
Laevatain Heat Team
 Laevatain |  Si |  Ardelia |  Arcane |
With Laevatain in Slot 1, Si's Battle Skill applies Heat Infliction instead of Cryo. Her Ultimate improves the team's Heat damage and reduces Laevatain's Combo Skill cooldown. Inksoul also helps keep attacks connected when enemies move away from Laevatain's damage windows.
Yvonne Cryo Team
 Yvonne |  Si |  Arcane |  Xaihi |
Si fits Yvonne's team by supplying another Cryo Infliction, along with additional Combo Skill damage and a stationary Inksoul target. This makes Yvonne's burst easier to land against fast-moving enemies without forcing major changes to her usual damage setup.
Si Rotation
Si's rotation depends on whether she supports a carry or acts as the main Combo Skill damage dealer.
General Si Rotation
Brushwork Realm → Initial Stroke (optional) → Build Cryo/Heat Inflictions → Ultimate before the main burst → Teammate consumes Inflictions → Fully Envisioned → Final Stroke when ready to detonate.
Use Initial Stroke when the Inksoul will help your team connect attacks. Otherwise, leaving Artful Intent on the original target avoids the extra SP cost.
For Si-centered Cryo teams, time her Ultimate to refresh her own Combo Skill and create another damage opportunity.
Si Potentials
| Potential | Effect |
| P1 – Spring and Autumn as Ink | Increases Immobilization duration, Artful Intent's recorded damage ratio, and explosion radius. |
| P2 – Three Marks Deep in Wood | Grants an ATK increase after using Fully Envisioned and scales with Infliction stacks consumed. |
| P3 – Study of Muscles and Bones | Increases Ultimate damage and strengthens its Cryo and Heat Amp effects. |
| P4 – Perfectly Composed in Spirit | Reduces Ultimate Energy cost by 15%. |
| P5 – Brush Dab in Eye's White | Increases Combo Skill damage, shortens its cooldown by 2 seconds, and counts an additional Infliction stack. |
P1 is a useful early upgrade because it improves Artful Intent's damage contribution. P2 provides another meaningful personal damage increase, while P5 offers the greatest overall improvement to Fully Envisioned. However, Si already provides her essential team utility at P0.
Is Si Worth Pulling?
Arknights: Endfield Si is a valuable choice for players who use Cryo or Heat teams. Her combination of elemental amplification, powerful Combo Skill damage, Artful Intent explosions, and Inksoul utility gives her several ways to improve a squad. She is appealing for accounts built around Yvonne, Laevatain, or Cryo-focused reaction teams.
However, players who use Physical, Electric, or Nature damage dealers will get less direct benefit from her elemental buffs. Jade Vessel and additional Potentials increase her damage, but neither is necessary to access her core support mechanics. If your roster already has strong Cryo or Heat carries, Si at P0 is a sensible investment.
Conclusion
Si brings an unusual mix of offensive support and personal damage to Arknights: Endfield. Jade Vessel remains her strongest weapon, and Type 50 Yinglung makes excellent use of her powerful Combo Skill. With the right first-slot operator and teammates who can consume elemental Inflictions, a solid Arknights: Endfield Si build can perform well in both Cryo and Heat compositions.
If you are planning to add Si to your team or aim for Jade Vessel, visit BuffBuff for Arknights: Endfield top-ups at attractive rates and prepare for your next pulls.
Arknights: Endfield is a real-time strategy RPG that combines squad combat, exploration, and automated production.
