Yenisei Reverse: 1999 Complete Build Guide - Skills, Resonance & Meta Teams

Yenisei is a powerful 5-star Star Afflatus support in Reverse: 1999, excelling as a healer and shielder who provides exceptional defensive utility in challenging content like Reveries and high-end PvE. 

Her kit revolves around Max HP scaling, unique Flow stacks for resource generation, and rare Immunity application, making her a staple for sustain-heavy teams despite lacking mass healing. 

This complete build guide covers her skills in depth, optimal Resonance upgrades, and meta team compositions to maximize her potential in the current January 2026 meta.

Skills Breakdown

Yenisei's skills emphasize protection and self-sustain, starting with her Basic Incantation, Action Taker, which serves as a single-target Mental damage dealer that applies a crucial DMG Dealt debuff to enemies. 

At one-star, it deals 200% Mental DMG, but it shines at higher ranks: rank two inflicts DMG Dealt -20% for two rounds alongside 200% damage, while rank three ramps up to 350% Mental DMG and -25% DMG Dealt, helping mitigate incoming threats effectively. This debuff synergizes perfectly with her role, reducing enemy output while she builds her unique Flow stacks.

Her second Basic, Words of Water, is a targeted heal that recovers 15% of her Max HP to one ally and grants one stack of Sturdiness, which provides 25% DMG Taken Reduction when triggered. 

Upgraded versions enhance this dramatically—at rank two, it heals 25% Max HP to the primary target plus 15% to the lowest-HP ally with Sturdiness on both; rank three pushes primary healing to 40% Max HP and secondary to 25%, both with Sturdiness, turning her into a precise HP manager for fragile DPS carries. Sturdiness stacks consumably, encouraging strategic use to bolster team survival without overcommitting AP.

The star of her kit is her Ultimate, The Rapids Know All, a mass shield granting all allies Shield equal to 25% of her Max HP for two rounds, alongside one round of Immunity to Stats Down, Negative Statuses, and Control effects—vital against debuff-heavy bosses. 

She also gains two Flow stacks upon casting, a positive status unique to her that consumes to grant Moxie or Empower Incantation I (up to three stacks max), randomly boosting a incantation's star level for amplified effects. Flow enters battle with two stacks base, refreshing her cycle and enabling frequent Ultimates, making her Moxie economy robust.

Her passive, Overprotective, triggers on battle entry with two Flow stacks and consumes one Flow plus one Moxie for extra Moxie when casting rank 2/3 debuff Basics, fueling her Ultimate uptime seamlessly.

Resonance Enhancements

Resonating Yenisei unlocks her full potential, with priorities on levels that boost her shielding and Flow generation for endgame viability. 

At Resonance Level 1, Action Taker upgrades to 220%/230%/400% Mental DMG across ranks, sharpening her debuff tool without altering core function.

Level 2 adds one extra Flow stack on entry via Overprotective, totaling three initial stacks for immediate Moxie ramps or Empower procs, drastically improving early-game sustain. Level 3 enhances The Rapids Know All's Shield to 30% Max HP, a noticeable jump that scales massively with her HP-focused builds.

Further upgrades shine at Level 4, granting +8% Healing Done on entry through Overprotective, stacking multiplicatively with Psychube bonuses for crit-healable output. 

Level 5 caps core upgrades by pushing Shields to 35% Max HP, making her Ultimates fortress-like barriers capable of absorbing raid-level punishment. Aim for Resonance 10+ for stat thresholds, as her HP scaling demands it—full investment often outvalues some 6-stars in pure defense.

Optimal Builds and Psychubes

Build Yenisei as a Max HP monster with secondary Critical Rate, since her heals and Shields scale directly off Max HP (up to 7031 at Insight III Level 60), and healing crits amplify output. Her base Crit Technique is high, so stack ~50% Crit Rate via substats or Psychubes to ensure reliable procs without sacrificing HP.

Signature Psychube Beyond Wonderland is her pinnacle, offering HP% substats, debuff-triggered healing amps, and Crit Rate passives that leverage her Action Taker debuffs for bonus heals—perfect for her dual Basic playstyle. Placidity serves as a strong alternative pre-Resonance, emphasizing HP and defensive passives.

Melodies Old and New excels in DPS teams with its 8% HP, 12-16% Healing Bonus, and stacking ally DMG buffs (up to 9%), letting her contribute offensively while healing. 

Budget picks like Take the Hard Journey provide hefty Healing Bonus, while aggressive options such as Aurora After Winter suit Eureka-synergy teams (e.g., with Marcus or Flutterpage), granting 16% HP plus Crit DMG ramps per Eureka consumed.

Insight progression is straightforward: Insight I unlocks Flow consumption on debuff Basics for Moxie; Insight II adds 10% entry Healing Done; Insight III enables Flow consumption on heals for Empower Incantation I, supercharging her kit. Materials include Sharpodonty, Starlit Ascent pages, and others—prioritize to Insight III Level 60.

Meta Teams and Synergies

Yenisei's sustain prowess fits myriad meta comps, particularly those vulnerable to control or burst, like HP-loss teams or FUA nukers needing Immunity uptime. Pair her with Charlie in single-target sustain setups, where her targeted Words of Water manages his HP fluctuations precisely, complemented by Sturdiness to weather enemy spikes—her lack of mass heal is a non-issue here, as Charlie thrives on spot-healing.

In broader PvE like Prydwen's top teams, she slots into Bloodtithe or FUA cores (e.g., alongside Nautika, Semmelweis, Rubuska), providing Immunity and Shields to stabilize HP-bouncing rotations while Flow fuels her Ult cycle for 2-round Divine Yoik enablers. 

For mono-Plant or Marcus hypercarries, team her with Vila and Mercuria/Kakania: Vila's Song of Passion amps Marcus' Ult spam, while Yenisei's Shields protect the aggressive push, her Moxie gen ensuring frequent Immunity against DoT/counter mechanics.

Crit-stacking nukes shine with her, like Barcarola-Kiperina-Aleph-Regulus, where she replaces weaker shields for superior Immunity+heal crits, maintaining safety amid massive Crit ramps. 

Flex her into Poison/DoT like Tuesday-Isolde-Sotheby, debuffing foes with Action Taker to boost team output while shielding against retaliatory bursts. Avoid pure mass-heal reliant teams, favoring those valuing her debuff+Immunity niche.

Playstyle Tips

Cycle Basics aggressively: prioritize rank 3 Action Taker on priority targets for debuffs, weaving Words of Water for low-HP allies, consuming Flow to chain Ultimates every 1-2 turns. 

Her tankiness lets her frontline safely, entering with max Flow for Moxie bursts. In long fights, her Empower procs randomly elevate Shields or heals, so embrace variance—pair with Moxie batteries for consistency. She's meta-defining for control-heavy patches, outshining many 6-stars in versatility.