Dr. Ratio is set to be available for free starting 17th January 2024 for all players. Players will be able to claim the character for free (Eidolon 0) and he should be a valuable addition to any account. A lot of us feel that nothing is truly "free" and that there must be a catch. After all, we have seen how poorly Aloy was received in Honkai: Star Rail. Dr. Ratio's case is different and he just might be the best single-target DPS in Honkai Star Rail patch 1.6.
Dr. Ratio Brings Single-Target Firepower to the Path of the Hunt
Seele, the first 5-star limited Hunt character is a pseudo area-of-effect (AoE) character. Topaz, the second 5-star limited Hunt character has synergy with follow-up attacks and pairs well with non-Hunt characters like Kafka, Jing Yuan, Himeko and Clara.
We do not have a limited 5-star character that specializes heavily in single-target damage at the moment and that is about to change. While Dr. Ratio might not have the mob clearing potential of Seele or double DPS synergies like Topaz does, he takes all of the spotlight and excels at singlet-target scenarios. If an enemy even dares to look at you the wrong way, the doctor will remove it from existence.
A lot of players do not have Dan Heng: Imbibitor Lunae and if you are one of them, you should absolutely consider building him. There is a community-made resource by Kygen with calculations for his best light cones, relics and other gear that you can refer to for building him.
Best Dr. Ratio Light Cones, Ranked
Using Cruising in the Stellar Sea S5 as the baseline at 100% damage, here are how the light cones perform for Dr. Ratio according to theorycrafters.
Baptism of Pure Thought (122.8%)
Worrisome, Blissful (112.7%)
Swordplay S5 (105%)
Cruising in the Stellar Sea S5 (100%)
Only Silence Remains S5 (100%)
Cruising in the Stellar Sea has innate Crit Rate which should make building Dr. Ratio a lot easier if you are not going for his signature light cone. If you do not want to spend your Simulated Universe currency, Swordplay is an easily accessible option.
Best Dr. Ratio Relics, Ranked
Genius of Brilliant Stars (117.59% against Quantum weak enemies)
Wastelander of Banditry Desert (111%)
2-Piece Musketeer of Wild Wheat and 2-Piece Ashblazing Grand Duke (108.79%)
Genius of Brilliant Stars (108.63% against enemies without Quantum weakness)
No Cavern Relic Set (100%)
You want to build as much Crit Rate and Crit Damage as possible, with a 1:2 ratio. You also need 30% Effect Hit Rate to guarantee his personal debuffs and you should get at least 120 SPD, with 134 SPD being the ideal breakpoint for Memory of Chaos.
Best Dr. Ratio Planar Ornamnts, Ranked
Firmament Frontline Glamoth (109% with 135 SPD and ATK Orb)
Inert Salsotto (108.31%, Recommended)
Space Sealing Station (107.83%)
Rutilant Arena (105.19%)
The planar ornaments do not have stark differences in terms of damage and you should choose whichever set you have the best sub-stats on. An ATK% Orb is a completely valid option for Dr. Ratio thanks to his high base ATK.
Best teammates for Dr. Ratio
Dr. Ratio synergizes with characters that can offer debuffs as well as universal supports like Bronya and Ruan Mei. You want to stack at least a couple of debuffs from teammates in addition to his personal debuffs to maximize his damage:
Pela (debuffer)
Guinaifen with Resolution Shines as Pearls of Sweat S5 (debuffer/sub-DPS)
Silver Wolf (debuffer, potentially best-in-slot teammate for Dr. Ratio)
Topaz (debuffer and follow-up synergy. E1 Topaz can be incredibly powerful with Dr. Ratio)
Bronya (buffer)
Ruan Mei (buffer/debuffer)
Fu Xuan (sustain and buffer) OR Huohuo (sustain and buffs)