Si is not a typical supporter. She deals real damage, rewrites rotation logic, and makes combat feel entirely different for the teams lucky enough to run her. Released with the Sanctuary of Ink version update in Arknights: Endfield, she adapts her elemental Inflictions to whoever leads your squad and creates a stationary Inksoul that lets your entire team dump resources without chasing a moving target. This guide covers everything you need to get the most out of her.
Who is Si and what makes her worth building?
Si is a 6-star Cryo Supporter who wields a Greatsword and scales primarily off Intellect, with Strength as her secondary attribute. She sits at the intersection of damage dealer and enabler: her personal Combo Skill output is genuinely high, but her real value is the Cryo and Heat amplification she provides through her Ultimate and the Inksoul mechanic that keeps enemies locked in place for your carry.
Her Artful Intent debuff records a portion of damage dealt to a marked target and releases it as Fixed DMG over a large area when the effect expires. Chain that with her Inksoul (a stationary copy of the enemy that redirects all damage and effects to the original), and you have a team that never loses a rotation to a boss teleporting across the arena.
Si operator profile overview
What are Si's skills and how do they work?
Basic Attack: Artistic Urge
Up to 5 attack sequences dealing Cryo DMG. When controlled, the final hit applies 18 Stagger. A finisher activates near a Staggered enemy for massive Cryo DMG and SP recovery. There is also a dive attack variant for mid-air approaches. Basic attacks matter more than you might expect since they run automatically when Si is off-field.
Battle Skill: Brushwork Realm
This is Si's setup tool and the key to most of her team's damage windows. Casting it deals Cryo DMG, applies Immobilization, marks the target with Artful Intent, and applies a Cryo or Heat Infliction depending on which element the operator in Team Position 01 uses.
After the initial cast, the Battle Skill transforms:
- Initial Stroke (costs 15 SP): Pulls an Inksoul from the Artful Intent target. All damage and effects applied to the Inksoul transfer to the host.
- Final Stroke (costs no SP): Destroys the Inksoul early, triggering a burst similar to Artful Intent's expiration damage.
If the host dies while the Inksoul is active, it links to another enemy and carries over the remaining Artful Intent duration without resetting it.
Combo Skill: Fully Envisioned
Triggers when an enemy's Cryo or Heat Infliction is consumed or absorbed. Si summons an Ink Lung dealing Cryo DMG scaled to the number of Infliction stacks consumed or absorbed from a single target. This is her primary damage source and the skill you want to fire as often as possible.
Si cannot trigger this herself. She needs teammates who consume or absorb elemental Inflictions, which is why team selection matters so much.
Ultimate: No One Spoils the Fun
Deals Cryo DMG in an area, grants temporary Cryo Amp and Heat Amp to the entire team, and reduces the Combo Skill cooldown of the operator in Team Position 01 by 20 seconds (via her Talent 1: Proxy's Patronage). That cooldown reduction is what enables rotations that simply do not exist without Si on the roster.
Talent 2: Unsoiled Brush
When the Inksoul disappears, all allied operators gain 30% Haste for 5 seconds. A useful passive that rewards you for completing the full Brushwork Realm sequence.
Brushwork Realm Inksoul setup
What is the best skill priority for Si?
Combo Skill > Ultimate > Battle Skill >= Basic Attack
| Skill | Target Level | Why |
|---|---|---|
| Fully Envisioned (Combo) | 12 | Primary burst damage, scales with Infliction stacks |
| No One Spoils the Fun (Ultimate) | 12 | Team Amp and Combo cooldown reduction |
| Brushwork Realm (Battle) | 9 | Artful Intent setup and Inksoul utility |
| Artistic Urge (Basic) | 9 | Auto-attacks off-field, still contributes |
The Combo Skill is the clear priority. Every level increases the damage on what is already Si's highest-output move. The Ultimate follows closely because the Cryo and Heat Amp it provides multiplies the entire team's damage, not just hers. Keep the Battle Skill at level 7-9 while leveling other operators and come back to it once the top two are capped.
What are Si's Potentials worth unlocking?
- Potential 1: Improves Artful Intent's damage and AoE range.
- Potential 2: Grants an ATK% buff when casting the Combo Skill, meaning the Combo Skill itself benefits from the increased ATK. A significant damage jump.
- Potential 3: 20% increase to both the damage and Amp effect of her Ultimate, pushing Cryo/Heat Amp to 43% at M3.
- Potential 4: Enables some new rotations but unlikely to change your gear setup unless you are running a pure support configuration.
- Potential 5: The strongest individual Potential. One extra Infliction stack consumed translates to roughly an 8.7% damage increase, and that extra stack also benefits from the final 1.15x multiplier. For a 4-stack Combo, Potential 5 is a 25% damage increase, plus the reduced cooldown means you fire it more often. Potential 2 also gets stronger here since you gain more ATK% from it.
Potentials 2 and 5 are the ones that change how Si plays. If you are investing in her for the long term, those are the targets.
What are the best weapons for Si?
Si is an Intellect Greatsword operator with limited weapon options. Khravengger technically works but gives Strength instead of Intellect, which costs a meaningful amount of final damage. Stick to the two options below unless resources force otherwise.
| Weapon | Rarity | Type | Best For |
|---|---|---|---|
| Jade Vessel | 6-star | Signature | Best-in-slot for all builds |
| Long Heritage | 6-star | Battle Pass | Best F2P/budget alternative |
| Khravengger | 6-star | Standard | Conditional, not recommended |
Jade Vessel (Best-in-slot)
Si's signature weapon. Base ATK 500, Intellect +156, Cryo DMG Dealt +43.3%, ATK +25.6%. When Si applies Immobilization, the target takes DMG Taken +12% for 30 seconds. After applying Immobilization or casting her Ultimate, her next Combo Skill within 20 seconds gains DMG Dealt +40%. The two effects apply separately.
The Immobilization comes from her Battle Skill, which means every Brushwork Realm cast activates both halves of this weapon. The DMG Taken debuff benefits the whole team, not just Si, making it a team-wide damage amplifier on top of her personal gains.
Long Heritage (Battle Pass alternative)
Base ATK 485, Intellect +156, Cryo DMG Dealt +43.3%, Main Attribute +11.2%. When her Battle Skill applies Cryo or Heat Infliction, Si gains Cryo DMG Dealt +9.6% for 20 seconds. When she grants Arts Amp to a teammate, the entire team gains Arts DMG Dealt +6.4% for 20 seconds.
The Arts Amp condition activates through her Ultimate, so both effects are consistently online. The team Arts DMG buff is smaller than Jade Vessel's DMG Taken debuff, but Long Heritage is still a strong option and the right call for players who did not pull Si's signature.
Jade Vessel weapon stats
What is the best gear for Si?
Damage-focused build (recommended for most players)
Gear Set: Type 50 Yinglung (3-piece)
The 3-piece bonus grants ATK +15% and builds Yinglung's Edge whenever any teammate casts a Battle Skill, stacking up to 3 times. Each stack adds DMG +20% to Si's next Combo Skill. In a team that regularly casts Battle Skills to build Inflictions, those stacks fill quickly and hit hard.
| Slot | Piece | Key Stat |
|---|---|---|
| Armor | Type 50 Yinglung Soft Armor | Intellect + Combo Skill DMG% |
| Gloves | Type 50 Yinglung Gloves v2 | Intellect + Combo Skill DMG% |
| Kit 1 | Type 50 Yinglung Beacon | Intellect + Combo Skill DMG% |
| Kit 2 | LYNX Slab | Main Attribute bonus |
Swap LYNX Slab for Redeemer Seal if you need more Ultimate Gain Efficiency to hit a rotation breakpoint.
Support-focused build
If another operator on your team already uses Type 50 Yinglung's set effect, you can run a mixed Eternal Xiranite setup on Si instead. Her Ultimate activates the set's team DMG buff, and pieces like the Channeling Gloves and Rangefinder keep Combo Skill DMG on the individual slots. Use Redeemer Armor in the body slot for Intellect and Ultimate Gain Efficiency.
This setup trades some personal damage for better team support. Only run it when a carry on your squad benefits more from the Yinglung set than Si does.
What are the best teams for Si?
Si's team building rule is simple: whoever is in Team Position 01 determines which element her Battle Skill applies. Put a Cryo operator first and she applies Cryo Inflictions. Put a Heat operator first and she applies Heat Inflictions. That flexibility is what lets her slot into multiple team archetypes without rebuilding her gear.
Si as main DPS: Si + Tangtang + Arcane + Xaihi
Si takes the first slot and acts as the primary damage dealer. Tangtang and Arcane both apply Cryo Inflictions, and Arcane can trigger Corrosion with her Battle Skill, which consumes Cryo stacks and activates Si's Combo Skill for a large damage window. Xaihi provides healing and additional amplification. This lineup works well for players who want Si to be the center of the rotation rather than a support piece.
For more detail on building around Si's Cryo carry role, the best F2P teams in Arknights: Endfield guide covers accessible options that pair well with this structure.
Si with Laevatain: Laevatain + Si + Camille + Wulfgard (or Ardelia)
Laevatain goes in Team Position 01, so Si's Battle Skill applies Heat Inflictions. Laevatain's absorption talent consumes Heat stacks, which triggers Si's Combo Skill. Camille and Wulfgard (or Ardelia for harder content requiring healing) round out the rotation. Si's Ultimate reduces Laevatain's Combo Skill cooldown, enabling faster burst cycles than Laevatain can achieve without her.
Si with Yvonne: Yvonne + Tangtang + Si + Xaihi
Yvonne benefits enormously from Inksoul. Her Ultimate requires her to stay on target, and Inksoul means she never has to chase a moving enemy during her damage window. Si applies Cryo Inflictions to keep Yvonne's consumption triggers available, while Tangtang stacks additional Cryo and provides Arts Susceptibility. Xaihi handles healing. Swap Xaihi for Tangtang if you need more Cryo application and can survive without dedicated healing.
Si with Last Rite: Last Rite + Tangtang + Si + Xaihi
Last Rite's Combo Skill consumes all Cryo Inflictions once a target has at least 3 stacks, which activates Si's Combo Skill. Last Rite also has limited AoE, and Si's Artful Intent partially compensates for that weakness by spreading recorded damage to nearby enemies when it expires. This is one of the more synergistic pairings in the current roster. Check the Last Rite build guide for the full rotation breakdown.
How should you play Si in combat?
Si's rotation changes depending on her role, but a few principles apply across all setups.
- Use the Ultimate before your main damage window. The Cryo and Heat Amp it grants needs to be active when your carry fires their big hits, and the Combo cooldown reduction for your Position 01 operator opens up rotations that would otherwise be impossible.
- Cast Brushwork Realm early in the rotation to get Artful Intent running. The longer it records damage, the bigger the burst when it expires.
- When you need the Inksoul, cast Initial Stroke immediately after Brushwork Realm. The stationary target locks your team's damage in place, which is especially valuable against bosses with high mobility.
- Trigger Si's Combo Skill whenever the condition is met, but do not break your team's rotation to chase it. If Laevatain is mid-combo and triggering it would disrupt her sequence, let the window pass.
- For the Final Stroke, use it to trigger an early Artful Intent burst when you need burst damage on demand rather than waiting for the natural expiration.
Common mistakes players make with Si
- Ignoring team position entirely. Si's Battle Skill element and her Ultimate's cooldown reduction both depend on who is in Position 01. Slotting her into a team without thinking about this wastes half her kit.
- Using Khravengger and expecting Jade Vessel numbers. The Strength substat and the conditional second passive make it a noticeably weaker option. Long Heritage is a better default if you do not have Jade Vessel.
- Stacking Ultimate Gain Efficiency when running a DPS build. Unless you are specifically building a pure support configuration, Type 50 Yinglung with LYNX Slab outperforms gear setups that sacrifice Combo Skill DMG for more frequent Ultimates.
- Forgetting that Potential 5 changes the math significantly. One extra Infliction stack on a 4-stack Combo is a 25% damage increase. If you are comparing Si's damage to other operators without accounting for Potentials, the comparison is not accurate.
Fully Envisioned combo skill burst
Frequently asked questions about Si
Should Si be in Team Position 01 or not?
It depends on the team. In a Si-centered Cryo lineup, putting her first lets her Ultimate reduce her own Combo cooldown, enabling consecutive burst windows. In a Laevatain or Yvonne team, the carry goes first so Si's Battle Skill applies the correct element and the cooldown reduction benefits the operator who needs it most.
Can Si work in F2P accounts?
Yes, with the right roster. Long Heritage covers the weapon slot without requiring her signature, and Type 50 Yinglung gear is farmable. The teams that work best with Si (Last Rite, Arcane, Tangtang, Xaihi) include operators available to most accounts. The ceiling is lower without Jade Vessel and high Potentials, but the core kit functions.
Does Si's Combo Skill work without Cryo teammates?
No. The Combo Skill triggers only when Cryo or Heat Inflictions are consumed or absorbed. If your team cannot apply those Inflictions, Si's Combo Skill never fires. This is the single most important team-building constraint when running her.
What happens to the Inksoul if the host dies?
If the host dies while the Inksoul is active, it automatically links to another enemy in combat and carries over the remaining Artful Intent duration without resetting it. If the host dies before the Inksoul is summoned, the defeated target drops an Inksoul at its location.
For a broader look at how Si fits into the current roster, the full Arknights: Endfield strategy guides cover weapon tier lists, operator builds, and team compositions across every major archetype.
