Castorice has fundamentally shifted the combat landscape in Honkai: Star Rail since her introduction. As a Quantum-type character following the Path of Remembrance, she introduces a unique gameplay loop that bypasses traditional Energy requirements. Instead of an Energy bar, Castorice utilizes the "New Bud" mechanic, a resource fueled by the HP fluctuations of her entire team. Building her correctly requires a departure from standard DPS archetypes, focusing heavily on Max HP and specific Relic synergies that reward a slower, more deliberate combat pace.

Core Mechanics and the New Bud System

Castorice operates through her unique resource, New Bud. The maximum limit of New Bud scales with the total levels of all characters present on the battlefield. Every single point of HP lost by any ally—whether through enemy attacks or Castorice’s own HP-draining Skill—contributes 1 point to New Bud. Once this gauge is filled, she can trigger her Ultimate, "Doom Shriek, Dawn's Chime," to summon the Netherwing memo sprite.

This mechanic means that Castorice is naturally Skill Point (SP) friendly. Her Skill, "Silence, Wraithfly's Caress," does not consume SP; instead, it drains 0.3% of the current HP from all allies to deal Quantum DMG and generate New Bud. This makes her an excellent fit for teams that are SP-hungry, as she contributes massive damage without competing for the team's primary resource.

The Netherwing itself is a backup unit, meaning enemies cannot target it directly. It inherits stats from Castorice and possesses a staggering base Speed of 165. Its primary attack, "Breath Scorches the Shadow," consumes its own HP to deal massive AoE Quantum DMG. Understanding that Netherwing’s performance is tied directly to Castorice’s Max HP is the first step in optimizing her build.

Best Light Cones for Castorice

The hierarchy of Light Cones for Castorice is strictly defined by her HP-scaling nature. Most standard Destruction or Erudition cones are useless here, as she follows the Path of Remembrance and requires specific stat sticks that boost durability and summon efficiency.

1. Make Farewells More Beautiful (Signature)

This is the undisputed Best-in-Slot (BiS). It provides a massive HP percentage boost and allows Castorice and Netherwing to ignore a significant portion of enemy DEF whenever they lose HP. Additionally, it features a unique action-advance mechanic that kicks in after the Netherwing disappears, allowing Castorice to restart her summoning cycle much faster. For those looking to maximize her ceiling, this Light Cone is almost mandatory.

2. To Evernight's Stars

A powerful secondary option often associated with premium Remembrance supports. It offers high base HP and a universal DMG boost that applies to the memo sprite. While it lacks the DEF shred of the signature, it remains a consistent performer in high-end content.

3. The Flower Remembers (Battle Pass)

For players who utilize the Nameless Honor, this is the most accessible high-tier option. It provides a stable Crit Rate buff and enhances the DMG of follow-up style attacks (which Netherwing's actions are categorized as in certain combat calculations).

4. Sweat Now, Cry Less

Another competitive alternative that focuses on enhancing the user's Crit DMG based on the current HP percentage. Since Castorice is almost always fluctuating in HP, the uptime on this cone's passive is remarkably high.

Relic and Planar Ornament Optimization

When it comes to Relics, Castorice is one of the few DPS characters where Speed is actively discouraged. This is due to her synergy with the specialized Remembrance gear sets.

Cavern Relics: Poet of Mourning Collapse (4-Piece)

This set was tailor-made for Castorice. The 2-piece set increases Quantum DMG, while the 4-piece set provides a massive Crit Rate boost to both the wearer and their memo sprite—but only if the wearer’s Speed remains low. Because Netherwing has its own fixed high Speed (165), Castorice herself does not need to move often. Keeping her slow ensures 100% uptime on the Poet set’s powerful Crit buffs.

Alternative: Longevous Disciple (4-Piece) can work if you haven't farmed a good Poet set yet, as the HP-drain from her skill easily triggers the Crit Rate stacks. However, it lacks the specific memo-sprite buffs found in the newer set.

Planar Ornaments: Bone Collection’s Serene Demesne

This set provides a baseline HP increase. Once the wearer’s Max HP hits a specific threshold (easily achievable on Castorice), it grants a substantial Crit DMG bonus. Given that Castorice’s damage scales directly with her health pool, this ornament set provides the highest numerical return on investment.

Alternative: The Wondrous Banana Amusement Park is a viable substitute if you are running her in a team that provides massive external HP buffs, as it further pushes her Crit DMG ceiling during the Netherwing’s active window.

Recommended Stat Thresholds

To ensure Castorice performs at an elite level in endgame modes like Memory of Chaos or Pure Fiction, aim for the following stats:

  • HP: 7,000+ (This is the most critical stat for both survival and damage scaling).
  • Crit Rate: Aim for 100% in-combat. With the Poet set and her traces, you only need about 60-70% on the stat sheet.
  • Crit DMG: 150%+ (Easily supplemented by supports and the Bone Collection set).
  • Speed: Base (Avoid Speed substats to maintain the Poet of Mourning Collapse set bonus).
  • Quantum DMG Sphere: While HP% spheres are viable, a Quantum DMG sphere usually results in higher total output unless your HP is critically low.

Trace Priority

  1. Talent (Desolation Across Palms): This governs the New Bud accumulation and the DMG boost stacks. It is the engine of her kit.
  2. Ultimate (Doom Shriek, Dawn’s Chime): Upgrading this increases the Netherwing’s base power and the RES PEN of the "Lost Netherland" territory.
  3. Skill (Silence, Wraithfly's Caress): Increases the initial Quantum hit and the efficiency of the HP-to-New Bud conversion.
  4. Basic ATK: Lowest priority. Only used when Netherwing is already active and you need to finish off a low-HP mob.

Don't forget her Bonus Abilities. Contained Dark Tide is essential as it allows healing to be converted into New Bud, making your healer a secondary battery for her summon.

Ideal Team Compositions

Castorice requires a specific team structure. Unlike traditional hypercarries, she does not want shielders (like Aventurine or Gepard) because shields prevent the HP loss required to generate New Bud. Instead, she thrives with high-output healers.

The Premium Hyper-Carry Team

  • DPS: Castorice
  • Support 1: Evernight (Provides massive HP-based buffs and Quantum RES reduction).
  • Support 2: Cyrene (Offers Turn Advance and boosts Crit DMG for summons).
  • Sustain: Hyacine (The BiS healer who can increase the team's Max HP and convert massive heals into New Bud points).

The F2P-Friendly Team

  • DPS: Castorice
  • Support 1: Remembrance Trailblazer (Ice) (Provides free Turn Advance and True DMG buffs that synergize with the path).
  • Support 2: Pela (Universal DEF shred is always valuable, especially for Quantum teams).
  • Sustain: Lynx (Increases Castorice’s Max HP and provides consistent healing to fuel New Bud).

The Dual-HP Drain Composition

  • DPS 1: Castorice
  • DPS 2: Blade or My Dei (Both characters consume their own HP, which rapidly charges Castorice’s New Bud gauge).
  • Support: Tribbie (Her high HP and universal buffs bridge the gap between two different scaling types).
  • Sustain: Gallagher (His Besotted debuff allows the team to heal themselves frequently, generating constant New Bud).

Strategic Combat Rotation

Playing Castorice is about managing the tempo of the New Bud gauge. At the start of a battle, use her Skill immediately. Even though it drains ally HP, the high Speed of most supports will allow them to act and be healed before the enemy moves.

Once the New Bud gauge is full, do not always fire the Ultimate immediately. Check if your supports have their buffs active. The Netherwing inherits Castorice’s stats at the moment of summoning. If you summon the Netherwing while under the effects of a 1-turn DMG boost from an ally, that boost effectively lasts for the Netherwing’s entire duration.

When Netherwing is on the field, focus on surviving. The Netherwing acts as a backup for the team—it will take the damage for allies if their HP is too low to be reduced further. This makes your team functionally immortal as long as the Netherwing has HP to spare. Use your healer's Ultimate during the Netherwing's turn to maximize the HP conversion via the Contained Dark Tide trace, ensuring the summon stays on the field for its full 3-turn cycle.

Eidolon Value Analysis

While Castorice is highly functional at E0, her early eidolons offer significant quality-of-life improvements:

  • E1 (Snowbound Maiden, Memory to Tomb): Significantly increases damage against enemies with HP below certain thresholds. This helps Netherwing execute bosses much faster.
  • E2 (Crown on Wings of Bloom): This is the gold standard for low-spenders. It allows Netherwing to ignore more DEF and provides Castorice with an immediate action after the summon, streamlining the rotation.
  • E6 (Await for Years to Loom): Pure game-breaking power. It grants massive Quantum RES PEN and allows the Netherwing to ignore enemy weakness types. At this level, Castorice can ignore the fundamental mechanics of the game, brute-forcing through any content regardless of elemental resistance.

Building Castorice is a rewarding experience for players who enjoy mechanical depth. By prioritizing Max HP, managing the HP-drain rhythm, and selecting teammates who can keep the cycle of withering and rebirth going, you can unleash the full potential of Aidonia’s daughter. Whether you are tackling the newest endgame challenges or simply looking for a unique Quantum carry, the Netherwing build remains a top-tier choice in the 2026 meta.