Dr. Ratio is a playable character in Honkai Star Rail. He is free for everyone to claim from the second half of Honkai Star Rail Version 1.6 up to the end of Version 2.1 as a thank-you gift from HoYoverse. Check out Dr. Ratio's Skills, Materials, Traces, and more here.

Dr. Ratio

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“A candid and self-centered Intelligentsia Guild member, who often conceals his appearance with a strange plaster sculpture.

He demonstrated unparalleled intelligence and talent since his youth, but now refers to himself as a ‘Mundanite.”

He firmly believes that intellect and creativity are not confined to geniuses. He seeks to distribute knowledge to the entire universe to cure the persistent disease named ignorance.”

Dr. Ratio is a 5-star Imaginary character on the Path of The Hunt. He has a Single Target-focused kit that also has some follow-up attacks weaved into it thanks to his Talent. His Talent also gives him a random buff that increases his offensive stats. He works well with debuffers but struggles in scenarios where AoE is needed.

Who are the Dr. Ratio Voice Actors?

For the English voiceover, Dr. Ratio is voiced by Jordan Paul Haro.

Dr. Ratio’s Japanese voice actor is Shunsuke Takeuchi. His previous roles include Producer from The iDOLM@STER Cinderella Girls anime series, Einar from Vinland Saga, and Harumi Takeda from Senpai ga Uzai Kouhai no Hanashi.

Dr. Ratio Signature Light Cone – Baptism of Pure Thought

The sunlight past noon shines just right, and the fragrance of flowers fills the air. Though he tries to keep his thoughts pure, exhaustion inevitably brings particulates of confusion like grains of dust.

“Healing one's thoughts is just as important as the maintenance of one's health.” The fools' clamoring fades alongside fatigue and he sinks into the water, letting all thoughts drift, letting his mind become clear and ordered.

“The truth will avert those of filth, and only those of purity can approach.”

Increases CRIT DMG for the wearer by 20/23/26/28/32%. Deals an additional 6/7/8/9/10% CRIT DMG to the enemy target for each debuff sustained, up to a maximum of 3 stacks. Grants Debate effect when attacking the target with an Ultimate, increasing DMG dealt by 36/42/48/54/60% while follow-up attacks ignore 16/18/20/22/24% of the target's DEF. This effect lasts for 2 turns.

Dr. Ratio Banner History

Dr. Ratio debuted on Honkai Star Rail Version 1.6. He is also available as a free 5-star character for all eligible Trailblazers who log in between the second half of Version 1.6 and Version 2.1.

Dr. Ratio Ascension Materials

Raising Dr. Ratio to Level 80 requires the following materials.

  • Antimatter Legion drops:
    • 15 Thief's Instinct
    • 15 Usurper's Scheme
    • 15 Conqueror's Will
  • Stagnant Shadow (Artisanship Commission) drops:
    • 65 Suppressing Edict
  • 887,800 Credits
  • (anything equivalent to) 5,797,920 EXP:
    • 289 Traveler's Guide
    • 3 Adventure Log
    • 3 Travel Encounters

Dr. Ratio Skill Materials

Maxing all of Dr. Ratio's Skills (Basic ATK to 6, Skill, Ultimate, and Talent to 10) will require the following materials.

  • Antimatter Legion drops:
    • 33 Thief's Instinct
    • 46 Usurper's Scheme
    • 28 Conqueror's Will
  • Calyx (Rivet Town) drops:
    • 12 Arrow of the Beast Hunter
    • 53 Arrow of the Demon Slayer
    • 101 Arrow of the Starchaser
  • Echo of War (Seclusion Zone) drops:
    • 9 Past Grievances of the Planet-Boring Disaster
  • 6 Tracks of Destiny
  • 2,197,500 Credits

Dr. Ratio Trace Materials

Activating all of Dr. Ratio's Traces will require the following materials.

  • Antimatter Legion drops:
    • 8 Thief's Instinct
    • 10 Usurper's Scheme
    • 30 Conqueror's Will
  • Calyx (Rivet Town) drops:
    • 6 Arrow of the Beast Hunter
    • 16 Arrow of the Demon Slayer
    • 38 Arrow of the Starchaser
  • Echo of War (Seclusion Zone) drops:
    • 3 Past Grievances of the Planet-Boring Disaster
  • 2 Tracks of Destiny
  • 802,500 Credits

Dr. Ratio Kit

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Numbers below are each Trace at Level 1.

Basic ATK – Mind is Might (Single Target)

  • Deals Imaginary DMG equal to 50% of Dr. Ratio's ATK to a single enemy.
  • Deals minor Imaginary DMG to a single target.

Skill – Intellectual Midwifery (Single Target)

  • Deals Imaginary DMG equal to 75% of Dr. Ratio's ATK to a single target enemy.
  • Deals Imaginary DMG to a single enemy.

Ultimate – Syllogistic Paradox (Single Target)

  • Deals Imaginary DMG equal to 144% of Dr. Ratio's ATK to a single target enemy and applies Wiseman's Folly. When Dr. Ratio's allies attack a target afflicted with Wiseman's Folly, Dr. Ratio launches his Talent's follow-up attack for 1 time against this target.
  • Wiseman's Folly can be triggered for up to 2 times and only affects the most recent target of Dr. Ratio's Ultimate. This trigger count resets after Dr. Ratio's Ultimate is used.
  • Deals Imaginary DMG to a single target enemy and applies Wiseman's Folly. When Dr. Ratio's allies attack a target afflicted with Wiseman's Folly, Dr. Ratio launches 1 follow-up attack on this target.

Talent – Cogito Ergo Sum (Enhance)

  • When using his Skill, Dr. Ratio has a 40% fixed chance of launching a follow-up attack against his target for 1 time, dealing Imaginary DMG equal to 135% of Dr. Ratio's ATK. For each debuff the target enemy has, the fixed chance of launching follow-up attack increases by 20%. If the target enemy is defeated before the follow-up attack triggers, the follow-up attack will be directed at a single random enemy instead.
  • When using the Skill, there is a chance of launching a follow-up attack against the target for 1 time.

Technique – Mold of Idolatry (Impair)

  • After using Technique, creates a special dimension that Taunts nearby enemies, lasting for 10 second(s). After entering battle with enemies in this special dimension, there is a 100% base chance to reduce each single enemy target's SPD by 15% for 2 turn(s). Only 1 dimension created by allies can exist at the same time.
  • Creates a special dimension. Enemies within the dimension are Taunted. After entering battle with enemies in this dimension, there is a high chance to reduce SPD of enemy targets.

Dr. Ratio Traces

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Indentation means dependency.

Summation (requires Ascension 2) – When Dr. Ratio uses his Skill, for every debuff on the target, his CRIT Rate increases by 2.5% and CRIT DMG by 5%. This effect can stack up to 6 time(s).

  • CRIT Rate +2.7% (requires Ascension 2)
    • ATK +4% (requires Ascension 3)

Inference (requires Ascension 4) – When Skill is used to attack an enemy target, there is a 100% base chance to reduce the attacked target's Effect RES by 10% for 2 turn(s).

  • ATK +6% (requires Ascension 4)
    • CRIT Rate +4% (requires Ascension 5)

Deduction (requires Ascension 6) – When dealing DMG to a target that has 3 or more debuff(s), for each debuff the target has, the DMG dealt by Dr. Ratio to this target increases by 10%, up to a maximum increase of 50%.

  • DEF +7.5% (requires Ascension 6)
    • CRIT Rate +5.3% (requires Lv. 75)
    • ATK +8% (requires Lv. 80)

ATK +4%

DEF +5% (requires Ascension 3)

ATK +6% (requires Ascension 5)

Dr. Ratio Eidolons

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Pride Comes Before a Fall

  • The maximum stackable count for the Trace “Summation” increases by 4. When a battle begins, immediately obtains 4 stacks of Summation. Needs to unlock Summation first.

The Divine Is in the Details

  • When his Talent's follow-up attack hits a target, for every debuff the target has, additionally deals Imaginary Additional DMG equal to 20% of Dr. Ratio's ATK. This effect can be triggered for a maximum of 4 time(s) during each follow-up attack.

Know Thyself

  • Ultimate Lv. +2, up to a maximum of Lv. 15.
  • Basic ATK Lv. +1, up to a maximum of Lv. 10.

Ignorance Is Blight

  • When triggering the Talent, additionally regenerates 15 Energy for Dr. Ratio.

Sic Itur Ad Astra

  • Skill Lv. +2, up to a maximum of Lv. 15.
  • Talent Lv. +2, up to a maximum of Lv. 15.

Vincit Omnia Veritas

  • Additionally increases the triggerable count for Wiseman's Folly by 1. The DMG dealt by the Talent's follow-up attack increases by 50%.

Dr. Ratio became playable on Honkai Star Rail Version 1.6, on the second half of the patch. Honkai: Star Rail is available for iOS, Android, Windows PC, and the Epic Games Store. Data taken from Honey Impact.