Honkai: Star RailDr. RatioBest build, teams and other guides

Dr. Ratio is a very powerful single-target damage dealer, given out for free to all players from 1.6 to until the start of 2.1. He specialises in dealing immense damage through follow-ups and accumulating permanent CRIT buffs in combat. He also benefits noticeably from attacking debuffed enemies, guaranteeing his follow-up at 3 debuffs and receiving a DMG bonus per stack, maxing out at 5 debuffs. The ways he can use his follow-up attack both provide more Energy over time than other characters and can somewhat alleviate the usual inherent weakness of Hunt characters.

The abrasive meme-lord with a heart of gold, Dr. Veritas Ratio finally graces us with his presence. Giving us the ability to play him early with a Trial version taught us much about his capabilities, and now that he’s here for real, it’s fairly apparent that he was actually holding out on us.

Before going into the usual breakdown, some important information first. Since debuffs are very important for Dr. Ratio’s kit, you should know what exactly constitutes a debuff in this game. The rule is this: if a Status Effect features a small red arrow pointing downwards, this is considered a debuff. If you are in doubt, you can inspect the Enemy Details window in combat and the Status Summary at the bottom will explicitly state how many debuffs they are currently afflicted with. If you don’t read this paragraph, you forfeit the right to complain later when you discover Hanya’s Burden isn’t a debuff.

Dr. Ratio’s Skill is a standard single-target Skill, dealing up to 150% of his ATK to a single enemy. This may initially seem rather low but this Skill works in tandem with his Talent as well as his Bonus Ability Traces, leading to far greater damage numbers for the meagre cost of 1 Skill Point.

His Talent is his main source of damage. When using his Skill, he has a 40% fixed chance to launch a follow-up attack against his target, dealing up to an impressive 270% ATK. Each debuff the target of his Skill is affected by will increase the fixed chance of this follow-up occurring by 20%. This means that if the targeted enemy has at least 3 debuffs on them, Dr. Ratio will always follow a Skill usage with a Talent follow-up, dealing a combined 420% ATK to a single enemy. Very dank, and very strong.

It should be noted that if his Skill defeats the target before the follow-up can be launched, Ratio will launch it anyway against a random other enemy. This prevents much of the value from being lost due to an early enemy death, but more importantly it helps to alleviate the natural downside of the Path of The Hunt, namely that they are exclusively single-target focused. In a similar sort of vein as Seele can use lesser enemies to bolster her offence, Ratio can pick off smaller foes and weakened stragglers and still deal damage against the remaining foes; with an upfront damage multiplier of 150% on his Skill, it is not unreasonable to expect this to deal with trash adds outright with proper setup. This automatically puts Ratio far ahead of pretty much all other Hunt units besides Seele.

Dr. Ratio’s Ultimate deals up to 240% ATK to a single enemy and applies a status effect called Wiseman’s Folly (it's not a debuff). Whenever allies attack a target with Wiseman’s Folly, Dr. Ratio will automatically launch a follow-up attack against them out of turn. This can happen 2 times before the status effect is automatically removed. This lasts indefinitely unless the afflicted enemy dies or until the trigger count is met.

This Ultimate allows Ratio to deal even more damage outside of his turn and use buffs even more efficiently. There is however an issue with this Ultimate, and that is that the debuff is removed when the enemy dies. It does not hop like Topaz’s Proof of Debt, meaning if an enemy dies before the trigger count is met for Ratio’s Ultimate, he completely loses the effects of the Ultimate. Given that this admittedly strong Ultimate has a steep cost of 140 Energy, losing its effects is miserable to have happen even if you’ve already gotten one follow-up off. Mostly if this happens, sorry, it’s a skill issue. This should only ever naturally occur at the very end of combat when it doesn’t matter anymore.

Another important thing to note is that because of the amount of follow-ups Ratio throws, his Energy economy is actually surprisingly good since each Talent follow-up gives 5 Energy; assuming you’re attacking an enemy with at least 3 debuffs, his Skill gives 35 Energy per cast, and his Ultimate provides 10 additional Energy once the Wiseman’s Folly follow-ups have been expended. The amount of follow-ups also contributes to a very impressive amount of overall Toughness damage, with each one dealing 30 Toughness damage, the same as a typical Basic ATK. Combining with his Skill again, each one of his turns he will be dealing 90 Toughness damage, the equivalent of all single-target Ultimates besides Xueyi’s.

Dr. Ratio’s Bonus Ability Traces provide some very powerful additional effects. A2 will provide permanent stacks of 2.5% CRIT Rate and 5% CRIT DMG whenever he uses his Skill against a debuffed enemy. The number of stacks he gets depends on the number of debuffs the enemy has on them, and he can have up to 6 stacks in total, granting 15% CRIT Rate and 30% CRIT DMG. This passive has sparked some confusion due to its wording, so to be as clear as possible, the bonuses do not need to be obtained concurrently; if an enemy has only 3 debuffs on them, you will gain the full 6 stacks after two Skill uses against them; if they only have 2, you will need three Skill uses to get the 6 stacks.

His A4 gives his Skill a 100% base chance to reduce the target’s Effect RES by 10% for 2 turns, giving Ratio an inherent debuff to apply to enemies. This debuff also becomes easier to maintain on enemies after its initial application due to the Effect RES reduction it provides. This also means teammates only need to provide 2 additional debuffs to meet the 100% follow-up chance on Skill use from his Talent. Do note that this debuff is only applied after the follow-up check occurs, meaning if you’re relying on this as your 3rd debuff, your first follow-up won’t have a 100% fixed chance to happen.

A6 will grant Ratio a DMG% buff for attacking debuffed enemies. This effect starts functioning at 3 debuffs and maxes out at 5, providing 10% DMG dealt for each debuff. This means that having 5 debuffs will give him a bonus 50% DMG dealt against the target with a 100% fixed chance to throw follow-ups on Skill uses, resulting in colossal damage output, but so long as you can meet the 3 debuff threshold for his Talent, 30% DMG dealt is perfectly acceptable as well. 100% chance for his follow-up is the most important milestone to reach, so don’t bend over backwards going for 5 debuffs if the team can’t attain it or if it’d result in a worse team composition.

Dr. Ratio also gets 12% CRIT Rate from his Minor Traces as well as 28% ATK. ‘Why are you mentioning ATK Traces?’ Because, as of the time of writing this, Dr. Ratio has the absolute highest Base ATK value in the game of 776, meaning ATK% bonuses will have a more noticeable impact on his overall ATK rating.

Dr. Ratio’s Eidolons are downright silly. Absolutely none of them are necessary in any way. Ratio is immaculate by default, at E0. However, for those… ‘Driven’ few who will pursue his Eidolons, you may see actual oneshots. E1 allows A6 CRIT buffs to stack to 10, E2 causes his follow-up to deal 20% additional ATK damage per debuff against debuffed enemies, up to an 80% ATK bonus per follow-up, E4 basically refills Ratio’s Energy bar in mere moments by giving 15 Energy back per follow-up, and E6 increases the number of Ultimate triggers to 3 while also increasing the DMG dealt by the follow-up by a massive 50%. I’m fully ready to see True Sting die to a singular piece of chalk.

As you can no doubt tell from what’s been said already, a very significant portion of Ratio’s total damage comes from his follow-up attack, but even more than that, it’s a majority of his damage. If you are unable to meet the minimum requirements of 3 debuffs to activate his follow-up attack, you will haemorrhage damage. There are only benefits to reap by meeting this baseline as it unlocks all the aforementioned great parts of his kit: his overall damage throughput, his remarkable Energy economy and Toughness damage, and even a minor ability to break out of his otherwise pure single-target damage profile.

As such, Ratio pairs very well with characters that can enable or amplify his capabilities. For the strongest single-target specialist team in the game, pairing him with Topaz is very powerful. Topaz has been waiting for a follow-up damage dealer who is able to both benefit from her debuff and increase the frequency of her own follow-up attacks, and Dr. Ratio fits that description perfectly. Ratio already deals so much single-target damage that it’s a viable strategy to focus down and kill summoner enemies outright, ignoring their summons entirely, and with Topaz’s powerful Vulnerability debuff, Ratio can do this even easier. Do note that without Topaz’s E1 or S1, you will need to find a source of at least 1 more debuff.

To that end, the usual suite of Nihility debuffers are fantastic to round out the rest of the team. It’s important to know that all Nihility characters can equip the Light Cone Resolution Shines As Pearls of Sweat, providing an extra debuff and decreasing enemies’ DEF. Pela can keep her Ultimate’s DEF Shred up pretty much indefinitely on all enemies, making it easier to switch to new targets when Ratio’s chalk deals the finishing blow, but it is only 1 consistent debuff without Resolution. Silver Wolf is understandably fantastic for racking up huge amounts of debuffs on single targets even at E0, and with the right setup, a single Skill usage from Silver Wolf can very nearly enable Dr. Ratio’s entire kit while also being able to ensure the enemy has an Imaginary Weakness thanks to her Skill’s Weakness Implant.

Guinaifen in particular is a very impressive character to pair with Ratio, as both her Burn and Firekiss Vulnerability count towards Ratio’s debuff count, simultaneously increasing his damage output and dealing good damage of her own. Especially in AoE scenarios, this can greatly offset Ratio’s weaker AoE capabilities by either dealing with smaller enemies outright, or by softening them up enough that Ratio can kill them with his Skill and then throw his follow-up on a completely different target.

If gaining enough debuffs is not a concern then Ratio of course also has access to the usual suite of Harmony characters as well. Bronya, Ruan Mei, and Tingyun are all very good at significantly increasing the damage Dr. Ratio can deal; Bronya can double Ratio’s action count with the right SPD tuning, Tingyun’s Benediction blessing getting a lot of value due to follow-ups not consuming it, and Ruan Mei for even faster and stronger Breaking. Ruan Mei in particular also provides a debuff of her own thanks to her Ultimate but, due to its cost, this should not be relied on to meet the minimum debuff threshold for Dr. Ratio.

A final note is that Dr. Ratio’s signature Light Cone is exceptionally powerful on him in particular. Ratio is absolutely fine and strong with the likes of Cruising in the Stellar Sea, but his performance goes up by that much more with his signature Light Cone, and it provides better quality of life than trying to maintain the passives of other Light Cone options. Again, Ratio is being evaluated here with the easily and freely accessible options and he’s already guaranteed to swat everything away with little effort, but he gets that much stronger with his sig. It’s very much a case of ‘gold versus platinum’ so it’s up to the individual to decide if they think it’s worth chasing that extra dazzle.

Dr. Ratio is not a complicated character once you’ve understood how he works, and he works with a vast array of other characters, fitting in nicely among the rest of the roster. Being given out for free as well means that everyone can benefit from his impeccable damage output, made even more valuable by being an Imaginary damage dealer, something that’s still lacking to this day. He has a few peculiarities that he needs met to really get going, but once he does he really gets going.

If you’re reading this from the future after 2.1 when Ratio leaves our collective inboxes, and you’ve missed out on getting him for free, you had ample time to pick the man up because that’s months away from the time I’m writing this. Take this L, sans the Ratio, obviously.

For the rest of us, the doctor… Is in.