Unpacking RES Shred vs RES PEN Mechanics in Honkai Star Rail
The Full Resistance Calculation Formula, No BS
Here's the deal: RES Multiplier = 100% - (RES% - RES PEN), clamped between -100% and 90%. Enemies start with base RES like 20% on neutral types, 0% on weaknesses, or 40% when they're feeling resistant. Take Swarm SAM—2,190,498 HP, 190 Speed, 200 Toughness—and top clears clock in at 52-68 seconds. Slap 10% RES PEN on that 20% RES? You're left with 10% effective RES, meaning a 90% multiplier.
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RES Shred: How This Team Debuff Actually Plays Out
RES Shred hits the enemy's base RES across your whole squad. Pela's Ultimate? Prime example. Sunday doesn't pack it himself, but his Ultimate dishes out 20% Max Energy (bump that to 40 with traces), and his Skill forward-advances an ally by 100% while stacking damage buffs.
RES PEN: Your Personal Damage Punch
This one's a selfish stat—purely amps your own hits. Ruan Mei's Ultimate throws 25-32% all-type PEN at foes. Sunday's substats? Forget RES PEN; chase Speed, CRIT DMG, HP, DEF, Effect RES instead. Fun fact: 20% RES PEN shakes out identical to 20% RES Shred in the formula.
When to Go All-In on Shred vs PEN
Shred shines in multi-element squads where everyone's chipping in. PEN? Hypercarry city. Sunday skips both on substats—Effect RES (aim 30%+ to unlock Broken Keel's 10% team CRIT DMG) and raw CRIT DMG for his Beatified buff take priority. Experienced players know: it's about stacking what he does bring to the table.
Sunday as the Imaginary Buffer King in 3.8 Meta
Breaking Down Sunday's Kit: Skills and Ult in Action
5-star Imaginary Harmony. Skill? 100% Advance on an ally (or summon), +30% DMG boost (+50% on summons for 2 turns), +20% CRIT Rate via Talent (3 turns), and +1 SP if they're Beatified. Ultimate drops Beatified: allies snag CRIT DMG equal to 30% of Sunday's own CRIT DMG +12%, ticking over 3 turns—but only on his turns. Oh, and 20% Max Energy (40 maxed).
Why Sunday Owns Imaginary Teams
Resonance synergy is chef's kiss for Imaginary comps—think Jing Yuan's summons getting that extra juice. Push 134+ Speed (just a hair under your DPS) for double cycles. Traces? Level Skill and Ultimate evenly, snag +25 start Energy, and that cleanse is clutch.
Sunday vs the Harmony Competition
S-Tier stuff. He's SP-positive (unlike Bronya's drain), outpaces Tingyun on energy, and vibes perfectly with Ruan Mei for her PEN. Sparkle demands 160+ Speed and feels niche by comparison. In practice, Sunday's the plug-and-play pick.
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Where Sunday Dominates Endgame Right Now
Fast Ult rotations melt high-HP Swarm SAM. He's single-target laser-focused for bosses—pop Technique for +50% first ability DMG. MoC, PF, AS? He crushes.
Swarm SAM Boss Breakdown and Its Resistance Quirks
Phases 1-3: What You're Up Against
Three phases on this beast: 2,190,498 HP, 190 Speed, 200 Toughness, 718 ATK, 115 DEF. Outspeed that 190 or bust—Super Break laughs at defenses. HP thresholds flip patterns and vulnerabilities.
RES Profile and Those Vulnerability Gaps
20% on non-weak hits, 0% weakness, 40% in defensive mode. Catch 1-2 turn windows at transitions. Imaginary isn't weak here, but Sunday's buffs bridge the gap.
Cracking Imaginary Weakness Without It Being One
Pair with Ruan Mei for PEN that mimics weakness. His CRIT DMG + Advance keeps pace with true weakness teams.
Pitfalls That Tank Your DPS
Speed your Sunday > DPS? Rotations crumble (stick 134+, one under DPS). Ult too early? Beatified vanishes. Effect RES under 30%? Kiss Broken Keel goodbye.
RES Shred vs RES PEN: The Numbers Don't Lie
20% Shred vs 20% PEN Math on 20% RES
Both drop effective RES to 0%, hitting 100% multiplier—a 25% DMG spike over baseline 80%. Dead even; your team comp picks the winner.
Sunday at 200% CRIT DMG? Beatified pumps 72% to allies—multiplicative mayhem.
Diminishing Returns: Don't Chase Ghosts
20% to 0%? 25% DMG. 0% to -20%? Just 20% more. Sunday's CRIT DMG scales Beatified linearly—pour there.
Real-World Damage from F2P Builds
F2P hitting 180%+ CRIT DMG gets 66% Beatified. That's trouncing a flat 25% RES cut.
Sunday's Substat Sweet Spot
Speed > CRIT DMG > Effect RES (30%+) > HP/DEF. RES PEN? Not even on the radar.
F2P Sunday Build: Substats Ranked Ruthlessly
Farm These First—Tiers That Matter
Tier 1: Speed (134+ baseline, 160+ for hyperspeed).
Tier 2: CRIT DMG (every 1% = 0.3% to allies).
Tier 3: Effect RES (30%+ for Broken Keel).
Tier 4: HP/DEF.
Keepers in Secondary Slots
ERR for Ult spam. ATK if it sneaks in.
Trash or Reroll These
Break Effect, non-Imaginary DMG Bonus, Healing Bonus, Effect Hit Rate—gone.
What F2P Can Realistically Hit
180%+ CRIT DMG scaling to 200%+; 134 Speed; 30%+ Effect RES. Grindable with patience.
Relic Sets and Main Stats That Slap for Sunday
Killer 4-Star and 5-Star Caverns
Sacerdos' 4pc: 6% Speed, 18% CRIT DMG to Skill/Ult targets (stacks up).
Hackerspace 2pc: Another 6% Speed.
Eagle 4pc: Hyperspeed at 168+.
Sacerdos + Hackerspace mix? 12% Speed, easy win.
Planars for Energy and RES Swagger
Broken Keel 2pc: 10% team CRIT DMG if 30%+ Effect RES.
Lushaka 2pc: 5% ERR, 12% lead ATK after Ult.
Fleet 2pc: 12% HP, 8% team ATK (120+ Speed).
Sprightly 2pc: ERR + opener Advance.
Main Stats, Slot by Slot
Body: CRIT DMG (HP/DEF backup).
Feet: Speed.
Sphere: HP/DEF%.
Rope: ERR.
F2P Farm Path
Sacerdos Cavern first—nail 4pc. Broken Keel only if Effect RES hits 30%+. Relic Remains for mains. Mix 2pc if RNG smiles.
Light Cones: F2P Staples to Whale Bait
4-Stars That Carry Sunday
Battle Isn't Over: ERR/SP regen +30-50% next ally DMG post-Skill.
Past/Future: 16-32% next ally DMG post-Ult.
Dance!: 16-24% team Advance post-Ult.
Rendezvous: Imaginary DMG if team matches.
5-Stars Side-by-Side
Grounded Ascent (Sig): +15-24% Energy/SP, Hymn DMG amp.
Earthly Escapade: 32-60% CRIT DMG + team CRIT.
Carve Moon: Roulette ATK/CRIT DMG/ERR.
Sig edges Eidolons, but don't sweat it.
S-Imp Priorities for Free Cones
Battle Isn't Over: 30→50% DMG.
Past/Future: 16→32% DMG.
How They Mesh with His Kit
ERR keeps Ults flowing; DMG buffs multiply Beatified; SP+ fuels Skill loops.
Teams and Rotations That Win Wars
Imaginary DPS Buddies Sunday Loves
Jing Yuan: Summon DMG +50%, buffs on buffs.
Imbibitor Lunae: Advance + CRIT for basics/Ult.
Welt: Debuffs + slows the pace.
Dr. Ratio: CRIT synergy for bursts.
Full F2P Squads, Ready to Copy
Core: Sunday + DPS + Asta (ATK/Speed) + Lynx (heal/cleanse).
Summon: Sunday + Jing Yuan + Tingyun (energy) + Gallagher (SP+ heal).
Hypercarry: Sunday + DPS + Pela (debuff) + Natasha (heal). DPS Speed 1+ over Sunday.
Rotation for Non-Stop Buffs
Weave: Technique → DPS Basic → Sunday Skill → DPS Double → Sunday Ult → DPS Burst.
Loop: Sunday Skill → DPS Double → Sunday Ult → Repeat. Never Skill on Harmony.
Energy and Ult Timing Hacks
+25 start Energy helps; sync Ult with DPS bursts. Beatified? Sunday turns only.
Trace Priorities When Mats Are Tight
Max These First
Even split: Skill/Ultimate.
High: Talent (CRIT Rate).
Low: Basic.
Medium: Bonus (40 Max Energy, +25 start).
Gains Per Level—Spend Smart
Lv1-6: Massive jumps. Lv7-9: Solid. Lv10: Meh. Perks: +37.3% CRIT DMG, 18% Effect RES, 12.5% DEF.
Ascension Mats Roadmap
Ascension: Tatters 15, Fragments 15, Shards 15, Chordal 65, Credits 308k.
Traces: Firmament 15, Tatters 41, Lost Echo 12, Tracks 8, Credits 3M. Weekly RNG hell—hit Calyx doubles.
Pro Tips to Dominate Swarm SAM
Phase Tweaks That Matter
P1 (100-67%): Buff city.
P2 (67-33%): Ult in safe spots.
P3 (33-0%): Chain Advances on vulns.
Debuff Timing Mastery
Pela def shred + Beatified stacks. Stagger for coverage; cleanse CC pressure.
F2P Traps and Dodges
Sunday > DPS Speed: Chaos. Early Ult: Gone. Low Effect RES: No Keel. Basic traces early: Wasted mats.
Building for Tomorrow's Meta
Summon focus preps future DPS; universal CRIT; energy for Ult-heavy friends.
FAQ
What is the difference between RES Shred and RES PEN in Honkai Star Rail?
RES Shred: team debuff on base RES. RES PEN: personal. Formula identical: 100% - (RES% - PEN); 20% each =25% DMG gain.
Does Sunday need RES Shred or RES PEN substats for Swarm SAM?
No RES PEN substats possible, no Shred ability. Prioritize Speed > CRIT DMG > Effect RES > HP/DEF; 200%+ CRIT DMG > RES manip.
What are the best F2P relics for Sunday Imaginary buffer?
Sacerdos 4pc: 6% Speed +18% CRIT DMG targets. Broken Keel (30%+ Effect RES): 10% team CRIT DMG. Body CRIT DMG, Feet Speed, Sphere HP/DEF, Rope ERR.
Can Sunday work without 5-star Light Cones in endgame content?
Yes; But the Battle Isn't Over (ERR/SP +30-50% DMG), Past and Future (16-32% DMG). Sig optimizes, not required.
What is the optimal substat distribution for Sunday in 3.8?
134+ Speed (1< DPS), 200%+ CRIT DMG, 30%+ Effect RES (Broken Keel), HP/DEF.
Which Imaginary DPS characters synergize best with Sunday?
Jing Yuan: summon dual buffs. Imbibitor Lunae: Advance/CRIT basics. Welt: debuff fix.
