Sunday is a five-star Imaginary Harmony support who gives an ally—and that ally’s summon—more turns, energy, damage, CRIT Rate and CRIT DMG. His Skill is the centerpiece: it advances a teammate’s action so a damage dealer can act, then act again. His Ultimate restores energy and applies The Beatified, while his Talent adds critical-rate support. That makes Sunday a turn-order and resource-management specialist rather than a damage dealer.
The mechanics and Eidolon figures below combine HoYoverse’s Version 2.7 announcement with creator-guide descriptions published around December 2024. Those guides are useful for understanding his intended play pattern, but they are not a verified October 2026 meta ranking. Check the live in-game descriptions for exact values and current availability before spending Stellar Jade.
What is Sunday’s role in Honkai: Star Rail?
Sunday is an Imaginary character on the Harmony path whose job is to amplify one important ally. HoYoverse describes him as a support who lets an ally and that ally’s summon immediately take action. He also regenerates part of a designated ally’s Energy and raises the ally’s and summon’s damage, CRIT Rate and CRIT DMG.
Why action advance matters
Most supports improve a team by adding a stat buff or reducing an enemy’s defenses. Sunday adds a second resource: time. By moving a chosen ally forward in the action order, he can let a carry attack earlier than expected and create another attack cycle within the same round. The value depends on who is being advanced, how fast the team is, and whether the encounter rewards concentrated damage on one target.
Who benefits from his summon support?
Sunday’s official role description explicitly includes summons. In a team built around a character whose summon acts separately, his buffs and action manipulation can affect both pieces of that damage pattern. The announcement establishes the coverage, but it does not establish a universal list of best partners; those choices depend on the live roster, speed buffs and encounter rules.
How does Sunday’s kit work?
Sunday’s kit is organized around a targeted Skill, an energy-restoring Ultimate and a Talent that supplies critical support. Community guides add several trace details, but exact live wording and values should be checked in the character screen because the guide descriptions are versioned.
Skill: advance an ally and improve damage
The Skill targets an ally and advances that character’s action while providing a damage buff. The action advance is the reason speed tuning is so important: the target can take a turn, Sunday can then use the Skill, and the same target can be brought forward for another action. One creator guide also describes a Skill-related trace that dispels one debuff from the target. Treat that as a trace effect to verify in your current client, not as a promise that Sunday cleanses every status or every teammate.
Ultimate: restore Energy and apply The Beatified
Sunday’s Ultimate restores Energy to a designated ally and applies The Beatified, his named support effect. Creator descriptions also mention a minimum Energy-restoration amount and a battle-start trace that grants initial Energy. Those are implementation details from a guide rather than figures stated in HoYoverse’s announcement, so read the current Ultimate and trace tooltips before calculating rotations.
Talent: critical-rate support
His Talent contributes CRIT Rate support. At higher Eidolon investment, the Talent becomes a much larger part of his buff package, including interactions with duration, Ultimate use and excess CRIT Rate. Without those upgrades, the Talent still reinforces Sunday’s role as a focused amplifier for a damage dealer rather than a personal attacker.
What does a typical Sunday turn sequence look like?
The common pattern is to let the carry act, then have Sunday advance that carry for another action. The exact order changes with speed buffs, enemy delays and the team’s Energy needs.
- Set the opening order. Arrange the carry and Sunday so the carry can take an initial turn before Sunday’s first Skill whenever the encounter and team buffs allow it.
- Use the carry’s first action. The damage dealer spends the opening turn applying its own buffs, attacking or setting up a summon.
- Use Sunday’s Skill on that same ally. The action advance moves the chosen ally forward and refreshes the relevant damage support.
- Take the advanced action. The carry attacks again, or performs the action that best exploits the team’s temporary buffs and summon timing.
- Use the Ultimate when its resource effect matters. Direct the Energy restoration and The Beatified toward the ally whose next cycle produces the greatest return, rather than firing it automatically on cooldown.
This rhythm is strongest when one character accounts for most of the team’s damage. It is less straightforward in teams that need several characters to act in a strict sequence, because advancing one ally can shift buffs, debuffs and summon turns out of alignment.
What do Sunday’s Eidolons change?
The creator guide highlights E1, E2, E4 and E6 as the major described upgrades. They add defense penetration, Skill Point economy, extra Energy or a broader Talent package. The effects below are the guide’s descriptions; they do not establish that any Eidolon is a good purchase for every account.
| Eidolon | Guide-described effect | Practical implication |
|---|---|---|
| E1 | The Skill target ignores 16% of enemy DEF when dealing damage, while the target’s summon ignores 40%, for two turns. | Raises the value of an advanced carry-and-summon sequence against enemies where defense mitigation matters. The different values for the ally and summon make the benefit roster-dependent. |
| E2 | Sunday’s first Ultimate restores two Skill Points and increases The Beatified’s damage by 30%. | Improves the first major Ultimate cycle and can relieve teams that spend Skill Points aggressively. Its practical value depends on how often the team reaches a second Sunday cycle. |
| E3 | Not detailed in the cited guide excerpt. | No effect should be inferred from this material; consult the current in-game Eidolon screen. |
| E4 | Sunday regenerates eight Energy at the start of his turn. | Can make his Ultimate rotation more reliable, particularly in encounters where he cannot generate enough Energy through normal actions alone. |
| E5 | Not detailed in the cited guide excerpt. | Do not assume an effect or value without checking the live game description. |
| E6 | Expands the Talent with stackable CRIT-rate support, longer duration, an Ultimate interaction and conversion of excess CRIT Rate into CRIT DMG. | Turns more of Sunday’s own critical-stat support into team value, but the return depends on the ally’s existing CRIT stats and the duration of the fight. |
How should you decide whether to pull Eidolons?
Start with the team’s actual bottleneck. If the carry routinely lacks turns, Energy or Skill Points, the corresponding upgrade may solve a visible problem. If the team already meets its rotation comfortably, an Eidolon’s theoretical damage increase may be less useful than saving for another character or Light Cone. No cited source provides a current 2026 cost-benefit ranking, pull-rate study or endgame damage comparison.
What is Sunday’s signature Light Cone?
A Grounded Ascent is Sunday’s signature five-star Harmony Light Cone. HoYoverse’s Version 2.7 announcement listed it in the “Brilliant Fixation: A Grounded Ascent” Light Cone Event Warp. That announcement confirms its Version 2.7 availability only; it does not establish whether the Light Cone is obtainable on a Warp in October 2026.
What the signature is intended to provide
A creator guide recommends A Grounded Ascent for the combination of Energy regeneration, ally damage support and Skill Point economy. Those functions line up with Sunday’s central rotation: keep his Ultimate available, support the advanced ally and avoid forcing the rest of the team to skip important Skills.
| Light Cone | How the guide characterizes it | When to consider it |
|---|---|---|
| A Grounded Ascent | Sunday’s signature option, focused on Energy regeneration, ally damage support and Skill Point economy. | When you want Sunday’s full intended support package and the Light Cone is actually available in your current account’s Warp rotation. |
| But the Battle Isn’t Over | Provides Energy and Skill Point support. | When stable Ultimate access and team resource generation matter more than matching the signature’s complete effect profile. |
| Past and Future | A lower-cost damage-buff alternative. | When you need a budget option and can reliably arrange the buff around the ally who acts after Sunday. |
The guide does not provide controlled damage tests between these Light Cones. Compare them by Energy needs, Skill Point consumption, buff coverage and duration, and whether the effect fits your planned action order. A lower-cost option that remains active every cycle can be more useful than a stronger effect that your team cannot trigger consistently.
How should you speed-tune Sunday?
A commonly recommended setup is the “-1 speed” pattern: Sunday is slightly slower than the primary damage dealer. The carry acts first, Sunday then uses his Skill, and the carry receives another action through the advance. This is a rotation concept, not a universal speed target.
Why the order works
If Sunday acts before the carry, his action advance may move the carry forward once, but the team can lose the extra natural turn that makes the sequence efficient. Placing him just below the carry lets the damage dealer spend its ordinary turn before Sunday’s Skill creates the second opportunity.
What can break a -1 setup
- Team-wide or temporary speed buffs can reverse the intended order.
- Enemy action delays, advance effects and wave transitions can change who acts next.
- A summon may have its own timing rules that do not mirror the owner’s turn.
- Some fights reward advancing a different ally, making a fixed carry-Sunday pairing suboptimal.
- Speed rounding and relic changes can erase a one-point gap, so verify the displayed order in battle rather than relying only on character-sheet values.
Build the order around the encounter you actually play. Test the opening round, the first Ultimate cycle and the first wave transition; if the carry no longer receives the intended second action, adjust speed or choose a different target.
What should you know about Sunday team comps and the 2026 meta?
Sunday is easiest to evaluate as a single-target amplifier whose value rises when one ally has a powerful action, a summon or an expensive Energy requirement. A sensible team-building checklist is:
- Primary damage pattern: identify the ally whose additional action produces the most damage or the most important setup.
- Energy demand: check whether the carry’s Ultimate timing improves when Sunday directs Energy to it.
- Skill Point budget: count the Skills used by the carry, sustain unit and secondary supports before choosing a Light Cone.
- Summon timing: confirm whether the summon benefits from the same buffs and whether advancing its owner creates the desired sequence.
- Turn-order stability: account for every speed or action-order effect in the team, including temporary buffs.
The available material does not establish Sunday’s current ranking against newer Harmony supports, his best 2026 teams or his performance in current endgame modes. It is therefore more accurate to describe his mechanics and decision points than to label him a universally best support. Competitive recommendations require a fresh comparison using the live roster, current enemy lineups and current game rules.
What should you verify before investing resources?
Open Sunday’s live character screen and confirm the wording of every Skill, Talent, trace and Eidolon. In particular, verify the debuff-dispel trace, Energy amounts, duration rules and any interaction involving The Beatified. Then test the intended speed order in the actual team, because relic upgrades and temporary buffs can change the result.
- Check the current patch number and read the in-game tooltips rather than copying an old guide’s values.
- Write down the carry’s real speed after all permanent and battle-start effects.
- Run one opening rotation and confirm that the carry acts before Sunday and again after the Skill when that is the goal.
- Record Skill Point and Energy totals at the end of the first cycle.
- Only then decide whether the signature Light Cone or an Eidolon addresses a demonstrated problem.
Frequently Asked Questions
Is Sunday a main DPS or a support?
He is designed as a Harmony support, not a primary damage dealer. His personal build and turn choices should serve the ally whose extra action, Energy and critical-stat buffs produce the team’s damage.
Can Sunday remove every debuff from an ally?
No broad cleanse guarantee is established here. A creator guide describes a trace that dispels one debuff from the Skill target, so check the current trace wording for its exact restriction and timing.
Is A Grounded Ascent available in the current Warp?
The official announcement confirms its appearance in the Version 2.7 “Brilliant Fixation” event only. Current October 2026 banner availability is not established, so consult the in-game Warp schedule before planning around it.
Should I copy a -1 speed build exactly?
Use it as a starting rotation, then verify your own action order. Speed buffs, summons, enemy delays and wave changes can make a slightly different order produce more consistent turns.