Master of Order: The Ultimate Sunday Build Guide (Honkai: Star Rail)

While his name might suggest a day of rest, Sunday is one of the most hardworking Harmony supports in Honkai: Star Rail. If you came here looking for a Zenless Zone Zero build, you might be in the wrong neighborhood—but if you want to turn your HSR hypercarries into unstoppable forces, you’re in the right place.

Sunday specializes in turn manipulation and massive CRIT DMG buffs, making him the premier choice for single-target carries and characters with summons (like Jing Yuan or Aglaea).

🛠️ The Best Sunday Build: Relics & Stats

Sunday’s kit scales off CRIT DMG, but his utility depends on how often he can act. Your goal is a balance of high speed and high crit.

Best Relic Sets

• 4pc Sacerdos’ Relived Ordeal: The undisputed Best-in-Slot (BiS). It maximizes his supportive capabilities.
• 2pc Sacerdos + 2pc Messenger Traversing Hackerspace: A great fallback option if you have better substats on your SPD pieces.

Best Planar Ornaments

• Broken Keel: The standard choice for boosting the entire team's CRIT DMG.
• Lushaka, the Sunken Seas: Excellent for hypercarry teams to funnel ATK to your primary DPS.
• Sprightly Vonwacq: Use this if you need that extra Energy Regen bump to hit specific ultimate rotations.

Recommended Main Stats

Gear Piece	Main Stat
Body	CRIT DMG
Feet	SPD
Sphere	HP% or DEF% (Survival)
Rope	Energy Regeneration Rate

Substat Priority: SPD (to breakpoint) > CRIT DMG > Effect RES > HP%/DEF%.

🏎️ Speed Tuning: Two Ways to Play

How you build Sunday’s speed depends entirely on your DPS:

1. The "-1 SPD" Setup: Build Sunday exactly 1 SPD slower than your DPS. Your DPS acts, then Sunday immediately uses his Skill to let them act again.
2. The "Hyper-Speed" Setup (160+ SPD): Stack as much speed as possible. This allows Sunday to drag a "slow" DPS (one with zero speed investment) up the action bar constantly.

🎼 Best Light Cones

1. A Grounded Ascent (Signature): His BiS. It provides everything he needs for consistency and team-wide buffs.
2. But the Battle Isn’t Over: The best premium alternative for Energy Regen and Skill Point (SP) recovery.
3. Past and Future: The best F2P/4-star option. Since Sunday's Skill advances an ally, they will almost always benefit from this cone’s DMG buff.
4. Earthly Escapade: Another strong choice if you have it available from other characters.

✨ Eidolons: Are They Worth It?

Sunday is a powerhouse at E0, but if you’re looking to invest further, here is the breakdown:

E1: The Power Spike

Verdict: Highly Recommended.
E1 adds DEF Ignore/Shred to the ally he targets with his Skill. In the world of HSR, DEF shred is one of the most valuable damage multipliers, especially for summon-heavy teams.

E2: The Comfort Pick

Verdict: Optional.
E2 focuses on SP efficiency and rotation smoothness. It’s a great quality-of-life upgrade, but it doesn't offer the raw damage jump that E1 provides.

The Whale Tier (E6)

E6 is his ultimate ceiling, turning his buffs into a massive team-wide power surge. However, for most players, E1S1 (E1 plus his signature Light Cone) is the "Gold Standard" for efficiency.

👥 Best Team Comps

Sunday shines brightest when he can focus his attention on one person.

• Summon Carries: He has unique synergy with units that have summons.
• Single-Target Hypercarries: Anyone who benefits from acting twice in a single cycle.
• Who to avoid: He is generally less effective in Damage over Time (DoT) or Break Effect teams, where supports like Ruan Mei or Robin provide more relevant buffs.

Ready to bring Order to the Cosmos? Focus on that 160 SPD target and watch your DPS soar!