HSR Self-Modeling Resin Guide: ERR Rope vs Speed Boots

What Is Self-Modeling Resin?

SMR guarantees a main stat of your choice on Body, Feet, Planar Sphere, or Link Rope slots. Craft it via 1 SMR + 100 Relic Remains in the Omni-Synthesizer (Customized Synthesis). Unlocks at Trailblaze Level 40.

You get exactly 2 SMR per month — Nameless Honor free track Level 20 and paid track Level 50. That hard cap means every use carries real opportunity cost.

Version 3.5 update: SMR merges with Wishful Resin, expanding sub-stat locking:

• 1 SMR → 1 Wishful Resin (max 3 monthly)
• 1 Wishful Resin + 1 SMR + 100 Remains = locks 1 sub-stat
• 4 Wishful Resins + 1 SMR + 100 Remains = locks 2 sub-stats simultaneously

This makes SMR more powerful than ever — and more worth spending carefully.

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Speed Boots: Why They're Mathematically Special

HSR runs on an Action Value (AV) system — characters act when accumulated AV hits the action threshold. Lower AV = more frequent turns. Speed Boots deliver +25 flat SPD as a main stat, the single largest Speed gain from any one relic piece.

Critical Speed Breakpoints

• 134 SPD — 2 bonus turns across 5 Memory of Chaos cycles; baseline for most Harmony supports
• 143 SPD — common target for supports running specific DPS action-value chains
• 160 SPD — 3 bonus turns across 5 MoC cycles; premium breakpoint for top-tier Harmony buffers
• 200+ SPD — niche hyper-speed tuning for specific compositions

MoC cycle math: first cycle costs 150 AV, subsequent cycles cost 100 AV each. Hitting 160 SPD compounds across the entire fight — every buff, heal, and debuff lands more often.

Why Speed Boots Are Hard to Farm

Feet slot SPD main stat: 12% natural drop rate. You need statistically 40–80 Cavern of Corrosion runs just to see a Speed Boot — before substat quality. At 40 Trailblaze Power per run, that's 1,600–3,200 Power for the correct main stat alone. SMR eliminates that variance instantly.

Speed is also multiplicative: a support at 160 SPD doesn't just act more — they buff, heal, and debuff more often, amplifying every teammate's output.

ERR Rope: When It Changes Everything

Energy Regeneration Rate accelerates Ultimate gauge fill. 20% ERR = 20% faster Ultimate cycling per action — meaningfully more casts per fight, especially in extended MoC encounters.

ERR Link Rope main stat: 5% natural drop rate — the rarest farmable main stat in the game. You need 100–200 Cavern runs naturally, consuming 4,000–8,000 Trailblaze Power. That's the strongest mathematical argument for ERR Rope SMR: farming cost is roughly 2.5× higher than Speed Boots.

When ERR Rope Transforms a Rotation

ERR Rope peaks in value when it shifts a character from a 3-turn to 2-turn Ultimate cycle. Prime candidates:

• Abundance healers (Luocha, Huohuo, Gallagher) — high-cost Ultimates where faster cycling directly improves team survivability
• Nihility debuffers (Pela, Silver Wolf) — tighter debuff reapplication windows

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The Core Math: Speed Boots vs. ERR Rope

No tables — here's the direct comparison:

Speed Boots (Feet SPD): 12% drop rate → 40–80 runs → 1,600–3,200 Power

ERR Rope (Link Rope ERR): 5% drop rate → 100–200 runs → 4,000–8,000 Power

Key insight: ERR Rope is statistically harder to farm, making it the more efficient SMR target in pure probability terms. But Speed Boots carry higher functional value for specific roles — Speed is breakpoint-dependent. A Harmony support missing 160 SPD by 5 points loses an entire bonus turn. No amount of substat farming compensates once you're that close to the threshold.

How Farming Volume Changes the Calculus

• F2P / low-volume farmers: Prioritize ERR Rope SMR — the natural farming cost is too high relative to your Power budget
• High-volume daily farmers: ERR Rope SMR is still the better spend since you'll eventually hit Speed Boots through volume alone

Priority by Role

Harmony Supports — Speed Boots First

Bronya, Ruan Mei, Sparkle, Robin, Tingyun, Asta — highest-priority Speed Boots SMR targets. Their entire value scales with turn frequency. Ruan Mei and Sparkle hitting 160 SPD means 3 additional buff windows per 5 MoC cycles for the whole team. Speed Boots SMR is almost always correct here regardless of ERR Rope efficiency.

Abundance Healers — ERR Rope First

Luocha, Huohuo, Gallagher — primary ERR Rope SMR candidates. Faster Ultimate cycling = more healing bursts and team-wide buffs. If a healer's rotation is one turn too slow for consistent coverage, ERR Rope SMR is the correct call.

DPS Characters — Lower Priority for Both

Hunt, Erudition, Destruction path characters (Feixiao, Firefly, Boothill, Acheron, Kafka, Black Swan, Jade, Yunli, Clara, Dr. Ratio) — Feet slot often targets ATK% or other stats, and energy generation is frequently supplemented by team composition. Spend SMR on supports first. DPS pieces can reach acceptable quality through farming volume.

Nihility Debuffers — Evaluate Case by Case

Pela, Silver Wolf, Kafka, Black Swan occupy middle ground. Speed matters for debuff reapplication; ERR Rope can be transformative if their Ultimate applies a key debuff. Use the 5-question checklist below.

Substat Floors: What to Expect After Crafting

SMR guarantees the main stat — not useful substats. A Speed Boot with flat HP, flat DEF, and Effect Hit Rate is technically correct but functionally weak.

Minimum acceptable substats for Speed Boots:

• At least 1 CRIT Rate or CRIT DMG line (DPS-adjacent supports)
• At least 1 ATK% or SPD substat line
• Avoid pieces where 3 of 4 starting substats are flat HP/DEF/ATK

Minimum acceptable substats for ERR Rope:

• At least 1 SPD substat line for supports
• At least 1 CRIT or ATK% line for offensive supports
• Pieces with Effect RES as the only useful line should be reconsidered

Pro tip: Hitting 160 SPD on a Speed Boot requires 21–27 additional SPD from substats depending on set bonuses. Average SPD substat roll is +2.3 per enhancement — you need approximately 9–10 SPD substat rolls to reach 160 SPD at +15. SMR solves the main stat problem, not the full optimization problem.

5-Question SMR Decision Checklist

Run through these in order before spending any SMR:

1. Does this character have a mandatory speed breakpoint? If yes and they're within 25 SPD of it, Speed Boots SMR is almost certainly correct.
2. Does ERR Rope meaningfully change this character's rotation? Calculate whether the energy gain shifts them from a 3-turn to 2-turn Ultimate cycle. If yes, ERR Rope SMR is high value.
3. Have I farmed this domain enough to assess natural drop rates? Fewer than 40 runs means you haven't given Speed Boots natural farming a fair chance.
4. Will this character stay meta for 2+ patches? SMR on a character who gets powercrept next patch is a poor long-term investment.
5. Does another character on my roster have higher SMR priority right now? Always compare across your full roster — the 2 SMR monthly cap makes relative priority critical.

Patch Timing and Strategic Hoarding

Don't hoard SMR indefinitely — every patch cycle you delay is 2 SMR you could have used. Practical threshold: maintain a buffer of 2–4 SMR before a major patch with confirmed new characters, then evaluate new releases within the first week using the checklist above.

Version 3.5 sub-stat locking system: 800 Relic Remains synthesize 1 Wishful Resin (capped at 2 monthly). A crafted Speed Boot with a locked SPD substat is now achievable — but requires significant Relic Remains investment alongside your SMR budget.

In practice: salvaging 5-star relics yields 10 Relic Remains each. Maintain an active salvage habit from every farming session to fuel both SMR synthesis and Wishful Resin production.

FAQ

What is Self-Modeling Resin used for in HSR? Synthesizes a relic with a guaranteed main stat of your choice for Body, Feet, Planar Sphere, or Link Rope slots. Combine 1 SMR + 100 Relic Remains in the Omni-Synthesizer. Doesn't affect Head (flat HP) or Hands (flat ATK) slots.

Should I use SMR on Speed Boots or ERR Rope first? Harmony supports targeting 160 SPD: Speed Boots first. Abundance healers and F2P players with limited farming volume: ERR Rope first, due to its 5% drop rate vs. 12% for Speed Boots.

How rare is SMR and how do I get more? Hard cap of 2 per month — Nameless Honor free track Level 20 and paid track Level 50. No other reliable recurring sources.

What speed gives 3 bonus turns in Memory of Chaos? 160 SPD yields 3 bonus turns across 5 MoC cycles. Speed Boots provide +25 flat SPD, and you'll need approximately 9–10 SPD substat rolls to reach 160 SPD depending on set bonuses.

Does ERR Rope affect Ultimate frequency? Yes. ERR directly accelerates Ultimate gauge fill. For high-cost Ultimates, ERR Rope can shift rotation from a 3-turn to 2-turn cycle — dramatically increasing buff or healing uptime in extended fights.

Is SMR worth using on DPS characters? Generally lower priority than supports. DPS pieces reach acceptable quality through farming volume. Harmony supports and Abundance healers have harder-to-farm main stats that are functionally critical to team performance. Supports first — unless a DPS has a specific breakpoint requirement.