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Dr. Ratio Honkai: Star Rail fighter artwork
Honkai: Star Rail Move & Ability Guide

Dr. Ratio moves, skills and special abilities

Move & Ability Guide

Dr. Ratio: 5-Star, Imaginary, The Hunt. Faction: Intelligentsia Guild — Erudition.

24 ability entries3 Skills1 Ultimate1 Talent2 Bonus Trace10 Stat Trace1 Technique6 Eidolon

Skills

3
Intellectual Midwifery
Skill

Inflicts Imaginary damage equal to 75% of Dr. Ratio's ATK to a single target enemy.

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Inference
Skill

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).

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Summation
Skill

When Dr. Ratio uses his Skill, for every debuff on the target, his CRIT Rate increases by 2.5% and CRIT damage by 5%. Maximum stacks: .

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.

Ultimates

1
Syllogistic Paradox
Ultimate

Inflicts Imaginary damage 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.

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.

Talent

1
Cogito, Ergo Sum
Talent

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 damage 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.

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.

Bonus Trace

2
Deduction
Bonus Trace

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

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Mind is Might
Bonus Trace

Inflicts Imaginary damage equal to 50% of Dr. Ratio's ATK to a single target enemy.

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.

Stat Trace

10
DEF Boost
Stat Trace

DEF increases by 7.5%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
ATK Boost
Stat Trace

ATK increases by 8%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
CRIT Rate Boost
Stat Trace

CRIT Rate increases by 5.3%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
ATK Boost
Stat Trace

ATK increases by 6%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
ATK Boost
Stat Trace

ATK increases by 4%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
ATK Boost
Stat Trace

ATK increases by 6%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
CRIT Rate Boost
Stat Trace

CRIT Rate increases by 4%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
CRIT Rate Boost
Stat Trace

CRIT Rate increases by 2.7%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
ATK Boost
Stat Trace

ATK increases by 4%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
DEF Boost
Stat Trace

DEF increases by 5%

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.

Technique

1
Mold of Idolatry
Technique

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.

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.

Eidolon

6
Pride Comes Before a Fall
Eidolon

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.

Requirements / unlock: Eidolon 1

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
The Divine Is in the Details
Eidolon

When his Talent's follow-up attack hits a target, for every debuff the target has, additionally inflicts Imaginary Additional damage 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.

Requirements / unlock: Eidolon 2

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Know Thyself
Eidolon

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

Requirements / unlock: Eidolon 3

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Ignorance Is Blight
Eidolon

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

Requirements / unlock: Eidolon 4

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Sic Itur Ad Astra
Eidolon

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

Requirements / unlock: Eidolon 5

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.
Vincit Omnia Veritas
Eidolon

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

Requirements / unlock: Eidolon 6

Source details & verification
HoYoWiki mechanics reference (community-editable), reviewed October 29, 2026. This is a concise mechanics index; the source contains full conditions and level-dependent scaling. Not independently tested in-game.