Most Operators in Arknights have skills; strong, triggerable abilities that can aid them or other Operators offensively or defensively by enhancing their stats, modifying their functionality, or giving them new capabilities altogether.
Only 3★ Operators and above have skills; 1★ and 2★ Operators have no skills whatsoever.
- 3★ Operators only have a single skill that is available initially.
- 4★ and 5★ Operators have two skills; the first is available initially and the second is available once they are promoted to Elite 1.
- 6★ Operators have three skills; the first is available initially, the second is available once they are promoted to Elite 1, and the third is available once they are promoted to Elite 2.
Operators with multiple skills can only choose one of them to be used at a given time, which is done from the Operator or squad menu.
Generally, the first skill is a generic skill shared across all Operators of the same class and/or branch, while the second and third skills are unique to each Operator and often act as core to the Operator's playstyle.
Usage[]
All skills cost SP (Skill Points) to use, which are generated in three different ways:
- Automatic Recovery: 1 SP is generated every second.
- Offensive Recovery: 1 SP is generated each time the unit attacks (including healing for Medics).
- Defensive Recovery: 1 SP is generated each time the unit is attacked, even if it is dodged or resisted.
Most skills start out with a number of SP already generated when the unit is deployed, which is referred to as "initial SP" and denoted by a white chevron prior to the skill's (green) required SP value:
Skills are activated in two different ways, both of which requires valid target(s) to be present within the skill's range if it requires one:
- Auto Trigger skills are activated as soon as the unit has enough SP, and, a valid target if such is required.
- Occasionally, a skill condition related to the skill's effect has to be met for the skill to be enabled.
- For instance, skills that give an Operator a deployable item, such as a fully-stocked Trapmaster, Silence's
Medical Drone or Shamare's Cursed Doll will remain at their maximum value without taking effect until the player uses that deployable. Once the player is eligible to acquire a new deployable, the skill will be used. - Flametail's Quick Intuition will not activate if Flametail still possesses the ability to dodge an attack from a previous cast of the skill, meaning that unless Flametail gets hit, she will not trigger any of the skill's effects, including its DP generation.
- For instance, skills that give an Operator a deployable item, such as a fully-stocked Trapmaster, Silence's
- Occasionally, a skill condition related to the skill's effect has to be met for the skill to be enabled.
- Manual Trigger skills are activated on the player's command, which can only be done when the unit has enough SP.
- Manual trigger skills are also subject to the rules as above, however, they are often designed with such mechanics that they are more unlikely to occur. It is still possible, however, for a manual ability to be impossible to cast due to not meeting a certain condition.
- Notoriously, Shift Specialists will not be able to push or pull enemies that are outside their range. If an enemy is blocked behind one such Operator's range, they will be in range for basic attacks, but not for skills. This is actually useful in certain complex stalling strategies, as using the skill will cancel the Operator's basic attack, resulting in them doing absolutely no damage.
- Manual trigger skills are also subject to the rules as above, however, they are often designed with such mechanics that they are more unlikely to occur. It is still possible, however, for a manual ability to be impossible to cast due to not meeting a certain condition.
Medical Drone
Cursed Doll
Quick IntuitionOccasionally, Operators have passive skills that are active at all times and do not require the player's input to function, although some are context-sensitive.
Most skills last for a short duration, but some skills last for an unlimited duration (actually for sufficiently long duration to be functionally unlimited in any stage, see Trivia for details). Some skills, that have instantaneous effects or modify the next basic attack, are regarded to have unlimited duration despite effectively not having any.
Some skills can store multiple charges, which means that while the skill is immediately usable after its SP cost has been acquired, the Operator can still charge SP for and store immediately available additional uses of the skill up to a limit. These skills can be either Auto or Manual, though they tend towards the former, and they tend to be exclusively instant effects.
Necrosis Damage prevents the victim from using their skill and causes them to lose 1 SP every second for 15 seconds (unless the skill is already active) after it procs.
There are some unique mechanics pertaining to skill usage:
| Mechanic | Information |
|---|---|
| Ammunition | Instead of lasting for a limited time, the skill lasts for a number of attacks and can be deactivated at will. |
| Overcharge | (Known as Charged in-game) The skill can generate additional SP after it is fully charged, up to twice the normal limit (e.g. a skill that costs 30 SP needs to generate a total of 60 SP to be Overcharged). Should the skill be activated once Overcharged, it will have additional effects. |
| Overload | When the skill's remaining duration is at most half of the total duration, it will have additional effects and certain drawbacks. |
SP Lockout[]
SP Lockout is the term used for the time an operator cannot be granted any SP to in any way. This includes direct SP granting like Saria's Refreshment talent or the Portable Supply Station (even though it is still depicted in the case of the latter, but there is no actual effect) as well as passive SP granting like Ptilopsis' Skill Aura talent. Operators who have Offensive or Defensive Recovery on their skill can still be granted SP to in a direct way, but will not benefit from passive SP granting.
Operators enter SP Lockout when:
- Their Manual Trigger skill is not activated. This is signified by a full green skill bar.
- Their Automatic Trigger skill is on, but is not activated due to there being no enemies within range (or in the case of Medics, no operators to heal). This is signified by an orange skill bar. An example case is Honeyberry's Spiritual Care.
- Their skill bar is in the process of depletion. This is signified by a depleting orange skill bar. For skills that are defined as an 'Instant Attack', this moment is the moment when the skill activates.
- Their skill is a passive effect. This is signified by a transparent skill bar. Example cases are Hoshiguma's Thorns and Manticore's Scorpion Venom
- Their skill is the generation of a Summon, but the summon is not deployed yet. This is signified by a transparent skill bar. Example cases are Silence's Medical Drone and Shamare's Cursed Doll.
- Their skill has finished charging and has an infinite duration. This is signified by an orange skill bar. Example cases are Thorns' Destreza and Skadi the Corrupting Heart's Wish of Burial Beyond the Light.
- Their skill has Ammunition and is turned on. This is signified by an orange skill bar that has vertical divisions representing the amount of ammo currently in possession. An example case is Aurora's Artificial Snowfall.
- Their skill has a maximum amount of uses within battle, and that maximum is reached. This is signified by a transparent skill bar. Example cases are Sussurro's Deep Healing and Guard Amiya's Ying Xiao - Shadowless.
Spiritual Care
Thorns
Scorpion Venom
Destreza
Wish of Burial Beyond the Light
Artificial Snowfall
Deep Healing
Ying Xiao - ShadowlessThe only operator truly capable of bypassing SP Lockout is Siege, due to her Crushing talent which is made to synergize with her skill 
Aerial Hammer. Operators who can Overcharge their skills can only bypass this state once, and they still enter it once their skill is finished Overcharging accordingly. Operators whose skill consists of an Instant Attack that can hold charges (i.e Ifrit's 
Pyroclasm) have no meaningful SP Lockout time, allowing effects like the Hand of Diffusion to work on an effectively continuous rate.
Operators who are affected by any of the bottom four causes mentioned cannot be forced out of SP Lockout without intervention of the player or from enemies that appear in the operator's range. For example, W will not place a Front Toward Enemy if there are no available tiles within her range to place them on, and one will not be able to activate Leonhardt's 
Deconstruct and Detonate if there are no enemies within his range.
Upgrades[]
Skills can be upgraded by leveling them from the Skill Upgrade menu on each Operator's Character Details page. Skills can be upgraded through 7 levels, and all of the Operator's skills (in case they have more than one skill) will be upgraded at the same time.
Upgrading skills require the following:
| Level | Skill Summary | Material(s) | Requirement(s) |
|---|---|---|---|
|
 1 |
– | – |
|
2 |
Few T1 upgrade materials | |
|
 1 |
Few T2 upgrade materials | |
|
Few T3 upgrade materials | Promoted to Elite 1 | |
| |||
|
 2 |
| Level | Skill Summary | Material(s) | Requirement(s) |
|---|---|---|---|
|
|
2 |
– | – |
|
|
Some/few T1 upgrade materials | ||
|
|
3 |
Some/few T2 upgrade materials | |
|
|
Promoted to Elite 1 | ||
|
|
Some/few T3 upgrade materials | ||
|
|
4 |
| Level | Skill Summary | Material(s) | Requirement(s) |
|---|---|---|---|
|
|
4 |
– | – |
|
|
Some T1 upgrade materials | ||
|
|
6 |
Some T2 upgrade materials | |
|
|
Promoted to Elite 1 | ||
|
|
Some T3 upgrade materials | ||
|
|
6 |
| Level | Skill Summary | Material(s) | Requirement(s) |
|---|---|---|---|
|
|
5 |
– | – |
|
|
Many T1 upgrade materials | ||
|
|
8 |
Many T2 upgrade materials | |
|
|
Promoted to Elite 1 | ||
|
|
Many T3 upgrade materials | ||
|
|
8 |
Mastery[]
Once the Operator's skills are at Level 7, they can be further improved to three additional levels through the Mastery (also known as Specialization) training function. Only 4★ Operators and above that have been promoted to Elite 2 can undergo Mastery training.
Mastery training is done at the Training Room of the RIIC. The process takes time to complete (which can be accelerated by assigning certain Operators as trainers), and unlike skill upgrades, are done individually for each skill.
Mastery trainings require the following:
| Level | Skill Summary | Materials | Time | Requirements |
|---|---|---|---|---|
|
2 |
Some/few T4 and T3 upgrade materials | 8 hours | Level 1 Training Room |
|
4 |
Some T4 upgrade materials | 16 hours | Level 2 Training Room |
|
6 |
Some/few T5 and T4 upgrade materials | 24 hours | Level 3 Training Room |
| Level | Skill Summary | Materials | Time | Requirements |
|---|---|---|---|---|
|
|
5 |
Some T4 and T3 upgrade materials | 8 hours | Level 1 Training Room |
|
|
6 |
Many/some T4 upgrade materials | 16 hours | Level 2 Training Room |
|
|
10 |
Some T5 and T4 upgrade materials | 24 hours | Level 3 Training Room |
| Level | Skill Summary | Materials | Time | Requirements |
|---|---|---|---|---|
|
|
8 |
Many/some T4 and T3 upgrade materials | 8 hours | Level 1 Training Room |
|
|
12 |
Many T4 upgrade materials | 16 hours | Level 2 Training Room |
|
|
15 |
Many/some T5 and T4 upgrade materials | 24 hours | Level 3 Training Room |
Tips[]
- Mastery training is very resource- and time-consuming, especially for 6★ Operators. Thus it is important to know how significant the boost to the skill will be and whether or not it is worth farming the materials for.
Trivia[]
- Skills with "unlimited" duration actually last for up to 60 minutes (30 if the game speed is doubled); however, the skill will almost never be deactivated during any operation as it greatly outlasts the average operation time.
- Furthermore, the skill ending rarely has any effect, as these skills are programmed to permanently update the Operator's status with the effects of the skill once turned on. They will still receive SP as normal, and can be enabled a second time once they initially end, but it will typically have no effect, unless the skill has an instant, immediate activation effect. For instance, activating a Command Terminal will not result in any change to its additional defensive buffs, but it will increase the deployment limit every time it is activated.
- Even though 1★ and 2★ operators have voice lines for skill activation, they can never be heard during operations, due to their lack of skills.
- As pointed out with the Command Terminal above, non-Operator deployable units and static units pre-placed in the level, both of which are known internally as "tokens" also use skills.
- Most enemy units, as well as environmental mechanics (that are controlled by invisible static units) like High Tide and the Londinium Secondary Defense Artillery use skills as well, although they are typically invisible from the player unless in specific cases like the Defense Artillery or the Sui-xiang's Omnidirectional Breath that clearly display an SP gauge, or Ishar'mla, Heart of Corruption, who openly displays the SP acquired as flyover text.
- That means most enemy ability timers are based in the same system of SP with different means of acquiring it (every hit/every second). The major difference, of course, is that enemy units can have several skills at once.