HSR V3.8 Sunday Build Guide: Relic, Light Cone & Teams

Sunday returns in Version 3.8, and became one of Phainon's best teammates! As a premier single-target buffer, he slots into ANY hypercarry team with instant action, massive damage boosts, energy refills, and debuff cleansing. If you are building Sunday in Version 3.8, here is everything you need to know to maximize his potential!

Ability Analysis: Precise single-target, Max Buffs

Skills priority:

Skill = Ultimate = Talent > Basic ATK

Skill:

Effect: Targets 1 ally (+ their Summons). Grants 100% Action Advance (they act immediately!) and DMG Boost for 2 turns.

Key Notes:

The 100% action advance effect is extremely powerful, allowing key allies (and their summons) to immediately take action. Summons will take their turn again right after the ally.
No Action Advance on other Harmony units.

When releasing Skill, removes 1 debuff from a single ally (identical to Bronya's Skill effect).
+20% CRIT Rate at max Trace(for 3 turns) . The CRIT Rate bonus is very impressive (A max-level 5-star CRIT Rate body piece only provides 32% CRIT Rate.)

 

Ultimate: 

Effect: Applies "Energy Halo" to 1 ally (+ their Summons). Lasts until Sunday takes 3 actions (at most 3 turns).

Energy Halo effect: Restores Energy equal to 20% of the target's Max Energy. Boosts CRIT DMG based on Sunday’s own CRIT DMG!

Scaling: Boosts the target's CRIT DMG based on Sunday’s own CRIT DMG stats!

 

Hidden mechanism:

Sunday has powerful bonus trace effects, making its mechanism more perfect:

• Start battle with +25 Energy → This makes him often have enough energy to immediately release Ult after releasing his Skill at the beginning.
• When using his Skill on a target with Energy Halo, Sunday restores 1 extra Skill Point. This means during Energy Halo’s duration, using his Skill becomes SP-neutral (or even SP-positive) – effectively free action advance!
• Ult’s Energy restore has a minimum of 40 Energy (great for low-Energy DPS like Dan Heng).
• Skill’s +20% CRIT Rate lasts 3 turns (with max Trace).

 

Relic Builds: SPD & CRIT DMG Optimization

Best Relic Set: Sacerdos’ Relived Ordeal (4-piece)

When Sunday uses a skill, it can further increase teammates' Crit DMG. Additionally, with a two-piece set, Sunday’s speed is boosted, allowing for more frequent skill usage.

Planar Ornament

Lushaka, the Sunken Seas

Provides 5% Energy Regen and boosts the ATK of the first character in the team lineup.

Broken Keel

A great alternative if you reach the 30% Effect RES threshold, providing 10% CRIT DMG to the whole team.

Main Stats

• Body: CRIT DMG%
• Feet: SPD
• Sphere: HP% or DEF%
• Link Rope: Energy Regeneration Rate

Sub Stats Priority

CRIT DMG > SPD > Effect RES > HP%

• CRIT DMG Goal: Initial Target ≥180% | Endgame Target ≥200%.
• SPD Goal: 134 for general play, or 1 SPD slower than your DPS to enable the "DPS → Sunday → DPS" loop.
•  Effect RES: Reach 30% to activate the Broken Keel bonus.
• HP%: Priority Basis: Survival stat (non-core). Official Kit Synergy: No direct kit interaction

Optimization Rules

1. CRIT DMG Focus

• Initial Target: ≥180% (post-trace unlock)
• Endgame Target: ≥200%
• *Example: CRIT DMG Body (64.8%) + 5 substat rolls (7.8% each) = 103.8% → Easily achievable*

2. SPD Thresholds

Scenario	Target SPD	Purpose
General Play	134	2 actions in first cycle
Speed Tuning	Less than DPS SPD	Enable "DPS → Sunday → DPS" loop

    
3. Effect RES Requirement

• 30% total activates Broken Keel's 10% team CRIT DMG
• Achieved via: Base 18% + two substat rolls (5.8% each)

4. HP% Positioning

• Only considered after CRIT DMG/SPD/Effect RES targets met
• Low-priority survival buffer

 

Light Cone Recommendations

Best Option (5-star):

A Grounded Ascent (Signature): Perfect synergy. It eases energy requirements, provides DMG buffs via the Hymn effect, and generates extra SP.

But the Battle Isn't Over (Bronya's LC): A strong second choice. Provides Energy Regen and SP recovery, though the DMG boost is less consistent than his signature.

Earthly Escapade (Ruan Mei's LC): Grants team-wide DMG boost (long duration) and restores Energy per wave. Useless Break Effect substat and no SP generation.

 

F2P & Budget Option (4-star):

Past and Future – The best F2P choice. Since Sunday advances an ally, they are guaranteed to receive this DMG boost.

Carve the Moon – Weave the Clouds: After using Skill, randomly boosts ATK/CRIT Rate/Energy Regen. Free to obtain and straightforward.

Dance! Dance! Dance! – Great for team-wide Action Advance on Ultimate.

Memories of the Past – Restores Energy when attacking. Consider for early-game or resource-limited builds.

 

Light Cone Priority Summary:

Signature LC > Bronya's LC ≈ Ruan Mei's LC > Carve the Moon, Weave the Clouds >Dance! Dance! Dance! > Memories of the Past.

Avoid These:

• [For Tomorrow's Journey] (Robin's LC): Short buffs + ATK% useless
• [Past and Future] ("Clockie" LC): Restrictive conditional buff
• [Planetary Rendezvous]: Only for Imaginary DPS
• Hanabi/Topaz LCs: Hard-to-maintain passive → becomes stat stick
• New 3.4 BP LCs: Break Effect/DoT focus → No synergy

 

Team Composition

Sunday excels in Summon-based and Hypercarry teams.

 

The Summon Specialists

Composition: Aglaea / Jing Yuan / Topaz + Sunday + Robin + Huohuo

Core Mechanics:

Simultaneous Advance: Sunday is the only support who grants a 100% Action Advance to both the character and their Summon (like Jing Yuan’s Lightning-Lord or Topaz’s Numby). This ensures the Summon attacks immediately after the character, preventing "wasted" stacks or slow cycles.

• Summon DMG Multiplier: His Skill provides a massive 50% extra DMG boost specifically for Summons, a unique multiplier that most other Harmony units lack.
• Robin Synergy: Sunday’s single-target pulling combined with Robin’s team-wide Action Advance creates a "pseudo-infinite" turn loop, allowing Summons to act multiple times within the first cycle of MoC.

 

V3.8 Hypercarry Teams

Composition: Phainon / Mydei + Sunday + Tribbie / Pela + Luocha / Gallagher

Core Mechanics:

Accelerated Mechanic Stacking: Many modern DPS characters rely on stacking "states." Sunday’s instant action allows Phainon to generate "Kindling" stacks rapidly and enables Mydei to stay in the "Godslayer Be God" state with much higher uptime.

• SP Neutrality: Because Sunday restores a Skill Point when targeting an ally under his Ultimate’s "Beatified" effect, he can pull these SP-hungry DPS characters repeatedly without draining the team's resources.
• Survivability via Cleansing: Sunday's ability to dispel a debuff with his Skill ensures your hypercarry is never CC-locked (frozen/imprisoned), which would otherwise ruin a high-damage rotation.

 

The "Double-Tap" Queens (Stack Generators)

Composition: Acheron / Feixiao + Sunday + Debuffer + Sustain

Bypassing Energy Limits: Acheron and Feixiao do not use traditional Energy for their Ultimates. While Sunday’s Energy refill is wasted on them, his 100% Action Advance is not. By moving twice in a row, Acheron applies double the debuffs for her Slashed Dream stacks, and Feixiao generates double the Flying Aureus points.

• Ultimate Burst Window: Sunday’s Ultimate provides a massive CRIT DMG buff that lasts for 3 of Sunday's turns. This ensures that when Acheron or Feixiao finally trigger their Ultimates, they are guaranteed to have the highest possible CRIT scaling active.
• Efficiency: He effectively turns a "slow" Acheron (0 SPD build) into a speed demon, allowing her to equip ATK% boots while still acting as if she has 160+ SPD.

 

Eidolons: Core Upgrades

E1:

• Using Skill → Target ignores 12% DEF
• With Summons: DEF ignore → 18%
• Massive DPS spike (like Topaz E1).

E2:

• Start battle: +8 Energy
• Use Ultimate: Recover 2 SP
• Energy Halo target: +30% DMG
• Fixes energy/SP economy + adds permanent DMG boost.

E4:

• Using Skill: +8 Energy
• Minor bonus.

E6:

• CRIT Rate buff: Stacks ×3 (max +60%), lasts 4 turns
• Ultimate also applies 1 stack
• CRIT Rate >100% → Excess converts to CRIT DMG (1%→2%)

 

Final Verdict: Greatness Needs No Explanation

Sunday is the new gold standard for Harmony supports in v3.8. His "buttery-smooth" kit—featuring 100% action advance for both allies and summons, massive CRIT boosts, and SP-positive rotations—makes him the ultimate versatile buffer. Whether at E0 or high investment, "Bro Sunday" is a transformative addition that elevates any hypercarry team to unprecedented heights. Greatness needs no explanation!

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