Magikarp Power / Arknights

Some operators are Boring, but Practical, functioning well even if they aren't (or can't be) upgraded further than Elite 1. However, there are many more operators, mostly six-stars, who don't hit their stride until they are properly raised, or only really start to be important at the endgame. But if you invest in them all the way until the end, then they will give you the bang for all the buck you spent.

Vanguards

• Muelsyse
  • Muelsyse is a curious case of Magikarp Power because her level of power is only partially depending on how high one raises her - due to her Power Copying talent being her entire backbone, Muelsyse only gets to be really powerful if you have other powerful operators like Dorothy, Mudrock and Eyjafjalla raised. Her summon clones 90% of a given operator's stats, so having a strong base is arguably a must if one wants to optimally use her. This means that Muelsyse is a powerful endgame option if anything. That aside, the summon's full power is only fully released once she hits Elite 2, and her second talent can be an essential bonus for herself in cases where a stage rushes you right out of the gate.

Casters

• Goldenglow
  • Casters within her branch rely on the Death of a Thousand Cuts trope, and on their drone which they can release to attack the same enemy. They often excel when attacking a single enemy together with their drone, to lose out on damage when more enemies get into the fray. At first, Goldenglow falls into this with an okay burst skill that increases her ASPD and ATK. When she reaches Elite 1, she gets to use her second skill, Surging Current, a permanent skill after a relatively long windup that releases her drones and widens her range. What's more important, however, is her gaining her talent Beacon's Wrath, which makes her stand out by letting her drones explode (each chance upping the 'pity counter'), occasionally giving her the chance to deal a lot of burst damage. Combined with her second skill, this makes for a lot more potential explosions. At Elite 2, she fully loses her chains. Not only does her talent gain an extra 100% Arts damage within its burst, her unique skill Crystalline Shine is unlocked along with its masteries, and she gains an extra talent that lets everything she does ignore a portion of the target's RES. The latter especially alleviates her Death of a Thousand Cuts trope indicated by her average ATK, but her third skill is a godsend when catching leaks or in situations like Integrated Strategies, letting her snipe dangerous enemies from a distance safely all the while inhibiting them with constant Slows and explosions. Even against enemies that can Draw Aggro or if she locks onto an undesired target, the chance of the explosions is usually enough to damage the nearby enemies as well.
• Ifrit
  • Whereas Ifrit has been a Caster who's available from launch, further developments both in the gameplay and in the system have made it so that fully utilizing the potential of Ifrit means a full investment. When you get Ifrit at first, she's a Difficult, but Awesome Caster whose quirky range is off-putting for what she gives in return. Her first skill is nothing noteworthy and her talents - the backbone of her kit - are only getting up to speed after at least one promotion. After that one promotion, her second skill, Pyroclasm is also unlocked, which fully utilizes her talent and adds a DEF debuff on it. However, for Ifrit to completely grow, a promotion to Elite 2 is necessary. At Elite 2, the most important thing is her third skill, Scorched Earth that is activated. While the HP drain on it cannot be lowered, it is also easily handled by a potent Medic, and it circumvents Ifrit's innately low attack speed by turning her range into a debuff area where enemies take constant Damage Over Time instead of just when she attacks. At this point, the first of her talents, Spiritual Dissolution, which debuffs the RES of all enemies within her range, goes from a -15% debuff to a -40% debuff, which is more than doubling its effectiveness and is enough for the debuff to really make a noticeable difference. Her second talent, Rhine Loop is just the cherry on top as it makes aforementioned skills (which have a low windup already) readily available whenever one wants it. This talent is also largely improved when Ifrit's module is upgraded, as she will now also have a chance to regain even more SP when her talent activates. Whereas this does involve RNG, it's done on purpose because otherwise, Ifrit would have no skill downtimes at all, period. All this investment is a large one, though, and due to the game's nature of its high-RES enemies being concentrated around the endgame (i.e chapter 9, Contingency Contract), this will mean that it's likely done when one has built their own base squad already, for all that entails.
• Lin
  • While Lin is a decent Phalanx Caster, she only starts to really shine once her module is unlocked and upgraded, as the module confers incredible buffs to her trait and talents, letting her retain half of the increased DEF and RES when her skill is active, and her second talent goes from a 50-55% chance to gain 1 SP when attacked, to a much more significant 75-80% chance to gain 2 SP when attacked, massively improving her skills' uptimes and making her a much more fearsome tank-nuker hybrid. The bonus stats from the module combined with her improved trait also let her completely shrug off all physical damage that deals 1250 damage or less, which is a major portion of enemy ranged attacks in the game, letting her tank attacks that would make even some Defenders shake in fear.
• Passenger
  • Whereas Passenger did get buffed after his lackluster release, almost all of the most potent buffs are accessible after two promotions in the form of his modules and the masteries on his skills, which he needs to perform optimally. His third skill, Glorious Shards, has a decent improvement in its multiplier upon mastery, but the reductions in SP cost make it much better than it is without them, making it so that investment in this skill is a fair necessity if one intends on using him seriously. As usual, both of his modules are only available after Elite 2, and even then, the most important changes happen at later stages. His X module decreases the low follow-up damage but will also give him a small SP battery of his own later on, severly cutting down his own downtime. His Y module focuses on the total damage instead, by directly removing the followup damage entirely and giving extra damage in his first talent. Getting there, however, will cost time, money and then some.

Guards

• In general, Centurion Guards (aka AoE Guards) have this going on in their growthline. Their main gimmick is the fact that they can attack all enemies they can block, which is 3. The point is that they don't reach that number unless they are raised to Elite 2, so they will be rather underwhelming right off the bat when you get them. They also have rather mediocre stats, so their output won't be great at first. At Elite 2, however, these stats gradually increase and more importantly, gain an extra block, making sure that they will be able to pull their weight effectively.
• Lappland
  • Lappland's main selling point is her sole talent, Spiritual Destruction, which silences anything she hits for 1 second. This short silencing time necessates her to practically camp a target for herself in order for her to silence it, as the 1 second is kind of finicky to work around. However, at her Elite 2 promotion, she gets her talent duration elongated to 5 seconds, enough for her to silence things permanently, and her second skill makes sure that she can also get out some respective damage and multi-target along with it. Notably, as there are more and more events that use enemies with silencable (and annoying) abilities, quite a number of players have gotten Lappland up to speed so that she can silence effectively.
• A lot of six-star Guards tend to be hit by this. Their most powerful kit is usually hidden behind their Elite 2 promotion, and even though a number of the most powerful ones do not have their module yet, it is guaranteed to get this trope in even more. To wit...
  • Executor the Ex Foedere
    • Executor the Ex Foedere is rather squishy like other operators in his branch and suffers from inconsistent damage due to the RNG nature of his The Chosen One talent, which makes him hit twice but starts at a 20%/23% chance that ramps up every time his skill consumes an ammo. Additionally, his main skill, Damnatus Ex Foedere, is locked behind Elite 2 and has a rather high SP requirement of 30 SP as an offensive recovery skill, which is reduced if his talent procs during normal attacks. Thus, mastering his third skill and upgrading his module after promoting him will allow him to reach his full potential by reducing the skill's SP cost to 24 SP, making him heal more, and alleviating the RNG nature of his talent by increasing its initial activation chance to 35%/38%, with a bonus of ignoring 300 DEF when it procs to boot, improving his damage potential while letting him charge up S3 quicker.
  • Mountain
    • Mountain starts out as nothing different from the others in his branch, sporting the same low ATK, and 1 block that the others also have. After Elite 1, his most used skill is already unlocked, which already improves upon everything a Guard of his kind would want to improve. However, it's not until you can master it and he gets his second talent that it can really shine. Masteries severly cut down its already short windup time, his aforementioned second talent helps with the DEF reduction in it, and the latter is also made smaller when it's fully mastered. Meanwhile, once fully mastered, the regeneration it gives makes it the most powerful self-heal on a single operator (an unconditional 7% HP per second), turning him into a beast at sustain.
  • SilverAsh
    • SilverAsh is most infamous for his True Sight, his redeployment timer reduction alleviating helidropping, and his third skill, all of which necessitate an Elite 2 promotion. Before that, he's a decent Guard as well, but relatively replaceable, especially considering that masteries on either of his first two skills cannot be done either. When you can master them, however, his first skill can pump out one of the highest numbers in a single attack, his second skill lets him become a potent self-healing tank like Mountain, and his third skill can make him into a annihilator if placed somewhere safe.
  • Skadi
    • After spending a long time as a Low-Tier Letdown, Skadi’s buffs in the form of her Module upgrade and Abyssal Hunter synergies brought her back to a respectable position in the metagame. While Skadi without her Module is considered one of the weakest 6-stars in the game, she becomes a monstrous force when her first Module is upgraded to level 3, as it reduces her redeployment time by 30 seconds, turning her into a pseudo-Specialist with massive stats that can be helidropped on multiple elite enemies within a single stage. However, Skadi truly comes into her own once she is paired with her fellow Abyssal Hunter Gladiia with her own Module upgrade, which grants all Abyssal Hunters a 30% reduction to Physical and Arts damage and 3.5% maximum health regeneration per second. This turns Skadi into a brutally powerful tank with huge DPS, to the point that she can pull off ridiculous feats such as soloing the Deathless Black Snake while also tanking the entirety of their Deathless Inferno attack without support. This power, however, is one of the most expensive to unlock in the game, requiring that you raise two 6-stars while also fully upgrading both their Modules, and can get even more expensive if you want more leverage ^note  Namely, the modules of Andreana and Specter the Unchained.
  • Thorns
    • Before Elite 2, Thorns' skill kit makes him play as a defensive but replaceable Lord guard with a decent Damage Over Time talent and Attack Reflector skill. After that, however, Thorns truly shines once he unlocks his third skill Destreza and second Talent Echoes of Ancestral Waves, which turn him into one of the strongest sustained laneholders in the game, capable of handling many threats at long range while fully regenerating his HP in between waves.

Defenders

• Mudrock
  • Mudrock doesn't start to be useful until she's at least promoted to Elite 1, as the skill she starts off with is a standard Defense-buff. Bringing her to Elite 1 gives her Crag Splitter, a skill that not only gives her some staying power via Life Drain, but also allows her to more effectively deal with a Zerg Rush using a Spin Attack. Once she gets to Elite 2, she gains Bloodline of Desecrated Earth, which, in exchange for a 10-second window in which she can't attack or be attacked, gives her extra DPS and a bit of crowd-control so that she can burst down a boss for the duration. Both of her promotions also increase the effectiveness of the healing from her Ward of the Fertile Soil talent, majorly upping her staying power.
• Penance
  • In order for Penance to fully live up to her status, she will need at least two promotions. Her first talent will not be able to outpace incoming damage, especially not in hectic levels with a Zerg Rush, and neither of her first 2 skills are particularly good at helping her survive even with her S2's defensive buffs. However, this will be a different story when that talent gets upgraded at Elite 1, as she will also regain it now when killing, while her second promotion buffs it up some more while giving her access to her Attack Reflector. Defenders usually have a low ATK, so you'd think that her killing enemies will happen sparingly, but that's what her third skill at Elite 2 is for, which majorly buffs her ATK and lets her instantly generate her barrier on demand, while also feeding into her thorns damage so that enemies practically kill themselves on her. After all of this, however, Penance can become a true Juggernaut who can absorb nearly unmatched amounts of damage while dishing out just as much in return.

Medics

• Reed the Flame Shadow
  • Reed the Flame Shadow is an exceptionally powerful unit that performs multiple roles within the squad once fully raised, due to her strong second and third skills which both scale incredibly well with Mastery (upwards of 24% and 51% in damage/healing output respectively, much higher than average Mastery gains), and the increased effectiveness of her Talent which debuffs enemy ATK and inflicts Arts Fragility which benefits her own and other units' DPS. Because of the different use cases of her S2 and S3, both are highly valuable for Mastery and allow Reed to excel in different situations depending on which skill is needed, as with her S3 she can use its Chain Lethality Enabler effect to near-instantly vaporize an entire map's worth of enemies, while with her S2 on two allies with both fireballs hitting the same target she has the highest potential DPS out of all Operators in the game. And since she is dealing such massive amounts of DPS and her healing scales with her damage dealt, she is simultaneously one of the best damage and healing units at the same time.

Supporters

• Ling
  • Ling is a monstrous Game Breaker who can flat out solo the majority of stages in the game, but her power only becomes apparent after promotion to Elite 2 at the very minimum. While her summons from her first and second skill are decent and still capable of clearing beginner or intermediate stages, the Thunderers she summons using her S3 are where her true power lies, with high stats and the Herd-Hitting Attack trait of Centurion Guards which double when combined in to their Higher Form, becoming units with absolutely monstrous stats and 4-Block that deal Arts damage with the only downside being that they cannot be healed and take two deployment slots each, the former being mitigated by just how tanky they are and the latter being near irrelevant when the Thunderers can easily clear most stages in the game on their own. Using Ling with her third skill is comparable to deploying multiple Blazes or Mudrocks within a single stage in terms of laneholding power—which is made more ridiculous if her Module is upgraded, which further buffs the stats of her summons, reduces their DP cost, and raises the maximum number of summons Ling can deploy by 1, which also raises the maximum number of Higher Form Thunderers to three. Additionally, as the stats of Ling's summons depend on her level, raising her to the level cap (usually considered inefficient for the amount of resources spent) is more valuable than other Operators as you are essentially improving the stats of multiple units at once, but the ultimate payoff is an Operator capable of being a literal One-Man Army who can clear most stages singlehandedly.

Specialists

• Aak
  • Aak is a somewhat unique case, as his strength is entirely relative to the development of the rest of your roster. Aak’s gimmick is in his ability to buff your allies with a steroid that either amps their defense with his S2 or their attack and attack speed with his S3. This buff, however, comes with a risk as he applies it by dealing a rapid barrage of damage to the target, which can and will kill them if they lack the health and defense to soak the damage. This means Aak is very dependent on the base stats of his allies to make sure they can survive his buff, and many Operators require help even if maxed. Certain Operators who buff defense such as Shining and Bison have their entire niche centered on making sure their allies can tank Aak’s skill and take advantage of his damage steroid. This means that Aak is a very beginner-unfriendly Operator that makes already strong Operators even better, but becomes a total liability for a weak roster.
• Specter the Unchained
  • Specter relies on her Dollkeeper mechanic to come back to life repetitively and on her Substitute, that can't block but continuously deals Arts Damage Over Time and slows anyone in its radius. At first, said Arts Damage Over Time and Slow won't be anything amazing (40%, and that percentage of her ATK) - to compare, Slow reduces the affected enemy's movement by 80% for as long as it's active. As it can't block, it renders the substitute as something to be avoided...unless you raise her to Elite 2 and get one of her modules. To wit, Module X raises the percentage of the movement speed reduction to 60%, and ups the damage of the substitute to 80%. This is enough for her to fully shine within her role, with the cherry on top being that in later stages, the module also gives her 15 SP when she tags back in, partially undoing one of the greatest weaknesses of the archetype (the fact that substitutes can't regenerate SP). On the other hand, Module Y makes her shine within an Abyssal Hunter team by giving them and herself extra HP and SP regeneration, and also makes Specter herself harder to kill.