Si Build: Gear, Weapon & Teams

Si overview

Si is a 6-star Supporter in Arknights: Endfield who fights with a Claymores and deals Cryo damage. The main attribute is Intellect and the secondary attribute is Strength. In the story, Si is affiliated with Hongshan Academy of Sciences. Si debuted on the Rejuvenation banner in Version 1.6 Phase 1, running 2026-10-15 to 2026-11-05, with Jade Vessel featured on the parallel Seal of Jade Issue weapon banner.

On the Endfield Hub general tier list, Si currently sits in S tier, the band labelled Optimal Assets (core anchors for specialized elemental cores or team archetypes). Version 1.6 limited Cryo Supporter and the first Greatsword Supporter. No One Spoils the Fun gives the whole team Cryo Amp and Heat Amp (20% to 36% by rank) for 12 seconds on an 80-energy Ultimate, Artful Intent banks part of the damage a target takes and returns it as Fixed DMG, and Proxy's Patronage cuts the slot 1 operator's combo cooldown by up to 20 seconds. She works in both Cryo and Heat teams, but her Combo Skill needs a teammate who consumes or absorbs Infliction and her Amp does nothing for Physical, Electric or Nature carries. Placed from her kit on launch day, before live testing.

How Si's kit plays

Si's basic attack, Artistic Urge, is a chain of up to 5 sequences dealing Cryo damage, and its Final Strike adds 18 Stagger when Si is the controlled operator. Used next to a Staggered enemy, it becomes a finisher that deals massive Cryo damage and recovers some SP. The Battle Skill, Brushwork Realm, costs 100 SP. Si deals Cryo DMG and applies Artful Intent, Immobilization, and Cryo Infliction (or Heat Infliction if a Heat element operator is in Team Position 01) on the target. After a target with Artful Intent takes DMG, part of the DMG taken is recorded.

Combo Skill Fully Envisioned triggers when an enemy's Cryo Infliction or Heat Infliction is consumed or absorbed. Its cooldown is 16s, dropping to 15s at its highest level. Si summons an Ink Lung that deals Cryo DMG. The Ultimate, No One Spoils the Fun, needs 80 Ultimate Energy. Si summons a Giant Ink Lung from her painting that deals Cryo DMG and grants temporary Cryo Amp and Heat Amp to the entire team.

Si carries 2 talents: Proxy's Patronage and Unsoiled Brush. At its highest rank, Proxy's Patronage upgrades the ultimate skill No One Spoils the Fun: After casting, Team Position 01 operator's combo skill cooldown length -20s. Unsoiled Brush, at its highest rank, reads as follows: When the Inksoul disappears, allied operators gain 30% Haste for 5s.

Building Si

In the weapon comparison above, Jade Vessel ranks first at R1 (Signature), ahead of Long Heritage (Protocol Pass at R1) and Khravengger (Owned fallback at R1). The most common gear loadout, used in 2 of 3 listed configurations, is Type 50 Yinglung Soft Armor, Eternal Xiranite Channeling Gloves and two copies of Type 50 Yinglung Beacon. Every piece is broken down in the Si gear set breakdown, and the artificing planner covers planning the artificing on those pieces.

Across the 3 recommended teams, the most frequent partners are Xaihi (2 of 3), Arcane (1 of 3) and Last Rite (1 of 3). Once talents pass level 9, the priority for Si runs Ultimate, then Combo, then Skill, then Basic. To compare Si with the rest of the roster, open operator builds or check where each partner lands on the tier list. The Si damage calculator on this page runs the numbers for any gear loadout.

Si potentials and upgrade costs

Si has 5 Potential ranks, and each one changes something specific. Potential 1 improves the battle skill Brushwork Realm: Duration of Immobilization applied +50%; Artful Intent DMG Record Ratio +7% and burst radius +40%. At Potential 2, this effect cannot stack.

Potential 3 improves the ultimate No One Spoils the Fun: DMG Dealt is increased to 1.2 times the original; Amp effect is increased to 1.2 times the original. Potential 4 improves the ultimate No One Spoils the Fun: Ultimate Energy cost -15%. Potential 5 improves the combo skill Fully Envisioned: Length of combo skill cooldown -2s and DMG Dealt is increased to 1.15 times the original.

Levelling Si from 1 to 90 takes 1,792,290 EXP and 385,420 T-Creds in total. There are 4 breakthrough stages, unlocking at levels 30, 40, 50 and 60. Together they cost 60 Protoset, 33 Protodisk, 20 Warp Plasma-Coated Slide, 8 Cosmagaric, 5 Red Bolete, 5 Ruby Bolete and 3 Pink Bolete, plus 126,100 T-Creds. The character progression planner tallies these against what you already own.

Raising all 4 skill groups through level 12 adds 688,800 T-Creds, and the largest material lines are 472 Protohedron, 328 Protoprism, 116 Tachyon Screening Lattice and 116 Metadiastima Photoemission Tube. Favorability bonuses add +60 Intellect in total, spread over 4 breakthrough stages. In the base, the factory skills are Ware is the Geist and Ink Spirit Aide. Assigned to the Reception Room, Ware is the Geist γ will grant operator clue collecting efficiency +30%. Assigned to the Reception Room, Ink Spirit Aide γ will slow Mood Drop of all operators in it by 18%. Every operator's base skills are compared in the operator base skills database.