Stationary Security Service

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Stationary Security Service (SSS or S3) is a game mode in Arknights. It is accessible from the Terminal since the Lingering Echoes update once 1-5 is cleared and after the player have unlocked an Operator Module.


SSS's gameplay is reminiscent to deck building card games such as Magic: The Gathering and Yu-Gi-Oh! in which players have to build a "deck" of Operators and clear sequential operations with them.

Playing SSS is needed if one wants to upgrade Operator Modules, as Data Supplement Stick.png Data Supplement Stick and Data Supplement Instrument.png Data Supplement Instrument – the materials to do so, are primarily obtained here.

To play SSS, the player must select a Security Mission, then choose the Directional EC Unit and Tactical Equipment for each class (explained below), and assign Operators to the squad, and finally start the mission. Like Contingency Contract and Integrated Strategies, SSS does not consume the player's Sanity.png Sanity to run.

After clearing a Security Mission added from the second rework for the first time, its Emergency Resupply mode will be unlocked. Playing in this mode doubles the rewards but applies a handicap, increases the initial Danger Level of each operation, and causes the player to start with Haywire EC Units (all of which are explained below).

Similar to I.S., the player may pause the mission by returning to the main menu and resume it anytime, and complete the mission prematurely from the mission menu. Unlike I.S., failing or quitting out of an SSS operation will not end the mission, instead returning the player to the mission menu where the current operation can be restarted. As such, the player can try SSS operations as many times as one wanted until cracked.


Unlike anywhere else, the player can include up to 20 Operators (including the Support Unit) in the Security Mission's squad. However, once the mission is started, the squad cannot be edited for the rest of the mission!

Upon clearing the LT-1, LT-2, LT-4, and LT-5 operations, the player will receive Temporary Reinforcements before starting the next operation, which expands the squad by 2 Operators of the player's choice from a selection of 5 random Operators for each (that can be forfeited). By LT-6, the squad will be made up of 28 Operators.

Which Operators that would appear as Reinforcements are determined by the Operator Strategy selected, chosen when building the initial squad before starting the Security Mission:

  • Preferred Plan: Prioritize Operators that are used often by the player, primarily those with the highest promotion.
  • Free Plan: Pick every Operator. Using this Operator Strategy also allows for Temporary Recruitment Operators to be available as Reinforcements at times, much like in Integrated Strategies which also extends to the Elite and Reserve Operators.

In an SSS operation, the are three places where an Operator may be.

  • Deployment Waiting Zone: Up to 12 units that are available for deployment will be present in the Deployment Waiting Zone. Keep in mind that summons tied to certain Operators will take up space in the Waiting Zone!
  • Preparation Area: Units that are waiting for deployment will be present in the Preparation Area. When the Prep. Area is empty, all units in the Recuperation Area (see below) will be reshuffled into the Prep. Area.
  • Recuperation Area: Operators and Directional EC Units (see below) that leave the map will be taken into the Recuperation Area.

When an SSS operation starts, the player will have 10 random units available in the Deployment Waiting Zone and may shuffle up to 4 units there with random ones in the Preparation Area (during which the game is paused).

Units in the Preparation Area can be transferred into the Deployment Waiting Zone automatically through certain means or manually at the cost of 10 Transfer Permits which is increased by 2 whenever units in the Recuperation Area are reshuffled into the Prep. Area, up to 20. Players start with 30 Transfer Permits in each SSS operation and can obtain more by:

  • Defeating an enemy, which gives 1 Permit.
  • At the start of breaks, where the player receives 40 Permits.
  • Certain Tactical Equipments:
    • Supporter A gives 15 Permits.
    • Vanguard B exchanges Tactical Equipment(s) passed by the relieved Operator into Permits at a 1:10 ratio.
  • The Reassignment Transmitter allows the player to remove up to two units in the Preparation Area in exchange for 15 Permits for every removed unit.

Certain methods allows the player to transfer units from the Recuperation Area.

Units transferred into the Deployment Waiting Zone can be redeployed immediately; only if the unit were taken right into the Waiting Zone upon leaving the map through certain means that their redeployment time counts down as normal. Regardless, Operators' DP cost still ramps up as usual.

Operators can be relieved by deploying one right on top of another (which is so far only possible in SSS), in which case the second Operator is immediately retreated and the first is deployed in their place. Because of this, it is possible to deploy an Operator if the Unit Limit is used up, but the Operator must relieve another (e.g. the player cannot relieve a deployed Robot Operator if doing so would exceed the Unit Limit).

Unlike anywhere else, when a deployed Operator's HP is reduced to 0, they will not be immediately knocked out, but rather enters a downed state for 20 seconds during which they are left with 1 HP and are invulnerable, but cannot attack, use skills, block enemies, and be healed in any way, giving the player an opportunity to relieve them. However, do note that certain skills and talents (e.g. Amiya's Chimera, Surtr's Remnant Ash) will not down the Operator, instantly KOing them!

Any changes on the Operators' stats will apply to the next operation in the Security Mission instead of the current one.

Tactical Equipment

Tactical Equipments are buffs that can be used to enhance the Operators or supporting their deployment in various ways.

Each class have two Tactical Equipments, A and B, but only one of them can be used at a time, which is chosen during the squad assigment and cannot be changed for the rest of the Security Mission! At first only Tactical Equipment A is available, while Tactical Equipment B is unlocked once the player completes an entire Security Mission for the first time.

When an Operator is relieved, they will pass on all of their Tactical Equipment(s) to the relieving Operator with certain exceptions (see below). However, if the Operator is knocked out or retreated directly (without relieving them), they will lose all Tactical Equipments they had. Passing on Tactical Equipments is important, as the Unit Limit in SSS operations are lower than in elsewhere and the Danger Level (explained below) progressively make enemies stronger, so the Equipments' buffs will help in overcoming the handicap.

A single Operator can benefit from up to five Tactical Equipments at a time, but certain Directional EC Units (see below) allow this limit to be surpassed.

Class A B
Caster icon.png
Grants the relieving Operator +20% ATK and +1 SP every 3 seconds Grants the relieving Operator +40% ATK
Defender icon.png
Grants the relieving Operator +40% DEF and +1 Block Grants the relieving Operator +25% DEF and +25% Max HP
Guard icon.png
Grants the relieving Operator +40% ATK Grants the relieving Operator +20% ATK and +20 ASPD
Medic icon.png
All units take 10% less damage After deployment, revive a downed Operator within range
Sniper icon.png
Grants the relieving Operator +40 ASPD Grants the relieving Operator +25% ATK and +25% Max HP
Specialist icon.png
After deployment, return retreated Operators to the Deployment Waiting Zone, and redeployment time -50% Grants the relieving operator +20 ASPD and +1 SP every 3 seconds
Supporter icon.png
After deployment, gain 15 Transfer Permits After deployment, view 4 random Operators in the Preparation Area, and choose 1 of them to transfer
Vanguard icon.png
Grants the relieving Operator +20% ATK and +1 SP every 3 seconds After deployment,[note 1] converts all Tactical Equipment to Transfer Permits (10 per equipment)
Additional information
  • Tactical Equipments that states "After deployment" cannot be passed on to the relieving Operator and are unaffected by Equipment Activation Valve.
  • All Tactical Equipments' effects on one particular attribute stack additively with similar effects from additional or other Equipments they passed on from the relieved Operator, but stacks multiplicatively with buffs and debuffs.
  • Medic B's revival works by immediately redeploying the downed Operator on the spot, thus their DP cost will ramp up as if they were knocked out or retreated.
    • Because of this, reviving a downed Supporter will cause their Tactical Equipment to activate.


Each Security Mission is divided into six operations distinguished by the "LT" code, except Security Drill missions which is made up of three operations distinguished with the "TR" code (not to be confused with tutorial operations).

Enemies in SSS operations spawn in three waves, with a 10-seconds Take a Break period or simply break in between them.

As with Contingency Contract, losing Life Points will not affect the final outcome of an SSS operation, so the player can let one or two enemies leak through if victory is to be assured.

Amplifier Device

All SSS operations feature an Amplifier Device, where every 50 seconds of the operation's time (which will be paused during breaks), the Danger Level will go up by 1; each Danger Level usually increases the HP and ATK/DEF of enemies by 25% and 5%, respectively (e.g. at Danger Level 10, enemies have +250% HP and +50% ATK/DEF), but some Security Missions may have different Danger Level effects; hostile devices are not subject to the Danger Level mechanic. As such, the longer it takes to clear the SSS operation, the more difficult enemies will be to deal with.

Each SSS operation has a set Danger Level at the start that increases in subsequent operations and a Danger Level cap that increases as the enemy waves progresses. Fortunately, Danger Level is not carried over between operations.

Operation Initial Wave 1 cap Wave 2 cap Wave 3 cap
LT-1 0 5 10 15
LT-2 1 5 10 15
LT-3 2 5 10 15
LT-4 3 5 10 15
LT-5 4 5 10 15
LT-6 5 10 15 20

In LT-3, the Danger Level cap will only be raised once the bonus wave is cleared (i.e. the cap will be of the previous wave instead of the next).

Unique enemies

All bosses unique to S3 are capable of disrupting Operator transfer and deployment as well as inflicting severe distractions towards friendly units. They are also excluded from the waves, so a wave can end with the boss still present, and deducts 3 LP upon entering a Protection Objective, thus they must be defeated lest the operation be instantly compromised!

Crude Sphere sprite.png
Fluorescent Originium Slug sprite.png
Small Symbiont sprite.png
Supersweetie Delivery Drone sprite.png
Fleet-footed Thief sprite.png
Teary Detective sprite.png
"Shiny Pooloo"
Spherical Colossus sprite.png
"Drifting Cabin"
"Fruit of Gluttony"
"Boy Wonder" Sandel
"Nature's Compromise"
Mama's "Rebel Girl"
"Supersweetie Smiley"
Thirster sprite.png

EC Units

SSS features unique deployable devices known as EC Units that are divided into three categories: Directional, Special, and Haywire.


Directional EC Units has both a passive effect that applies throughout the operation and an active effect that applies when the Directional EC Unit is deployed. Only one Directional EC Unit can be used at a time, which is chosen before starting a Security Mission and will be available in all operations of that Mission.

Directional EC Units will be taken into the Recuperation Area upon leaving the map with some being returned to the Deployment Waiting Zone instead, allowing them to be reused at the player's discretion.

After clearing the LT-3 operation, the Directional EC Unit can be upgraded with one of two Directional EC Components of the player's choice, modifying its functions or improving its effectiveness.


These Directional EC Units are available in all Security Missions.
EC Unit Use
Aegirian Oscilloscope.png
  • Passive: Increases the Tactical Equipment cap of Abyssal Hunters Operators (but they can only benefit from up to 5 of the same Tactical Equipment) and buffs their HP, ATK, and DEF.
  • Active: Can remove up to 2 out of 4 random Operators in the Preparation Area for the operation to give deployed Abyssal Hunters one Tactical Equipment of the removed Operators' respective class (or transfers an Abyssal Hunter Operator from the Prep. Area if none are deployed).
  • Directional EC Components
    • Assault Circuit Chip: Further increases the Tactical Equipment cap and gives an additional Tactical Equipment when Abyssal Hunters would receive one.
    • Ambush Circuit Chip: The deployed Oscilloscope remains for a while, during which enemies blocked by Abyssal Hunters are Stunned.
Adaptive Supply Component.png
Will always be in the Deployment Waiting Zone at the start of an operation.
  • Passive: Increases the initial SP of Operators.
  • Active: Periodically gives Transfer Permits equal to the amount of Operators in the squad.
  • Directional EC Components
    • Weapon Supply System: Casters and Snipers gain a double ATK buff for a short time after deployment.
    • Orientation Deployment Support System: Defenders and Specialists cost no DP. A unit will be transferred whenever an Operator is relieved, up to three times in an operation.
Energy Perturbation Amplifier.png
Introduced in Dispatch Cycle 2: Recapture Land.
  • Passive: Enemies that are being Slowed/Bound/Stunned/Chilled/Frozen/Levitated have their DEF and RES gradually reduced.
  • Active: Intermittently Slows/Binds/Stuns/Chills/Freezes/Levitates enemies within its radius for a short time.
  • Directional EC Components
    • Signal Blocker: Slowed/Bound/Levitated enemies take more damage.
    • Heteromorphic Accelerator: Stun/Cold/Freeze on enemies last twice as long.
Competition Records Analyzer.png
Introduced in Dispatch Cycle 3: Southern.
  • Passive: Kazimierzian Operators are returned to the Deployment Waiting Zone when relieving/relieved by another Kazimeirzian Operator, keeping their Tactical Equipments.
  • Active: Reduces the DP cost of Kazimierzian Operators in the Deployment Waiting Zone, then returns to the Waiting Zone.
  • Directional EC Components
    • Deep Computing Unit: All Operators have their ATK and ASPD increased for a short time whenever a Kazimierzian Operator is deployed.
    • Data Sharing Unit: Kazimierzian Operators have their ATK and DEF increased after being deployed for some time, which will be passed on to the relieving Kazimierzian Operator.


These Directional EC Units are only available in specific Security Missions.
EC Unit Use
Coating Device Conduction Valve.png
Can only be used in Under-Construction Dossoles Plate.
  • Passive: Buffs the max. HP and DEF of Defenders and Guards. Blocked enemies have their ATK and DEF intermittently reduced, up to a limit.
  • Active: Gives the Operator ahead a Barrier that also increases their block count through a skill that can store 2 charges.
  • Directional EC Components
    • Redeployment Conduction Component: Reduces the DP cost of units while in the Deployment Waiting Zone. Gives 1 charge to the Conduction Valve's skill and transfers a unit when deployed.
    • Counter Conduction Component: Increases the intermittent ATK/DEF reduction for blocked enemies and its cap. The Conducting Valve's Barrier does not increase block count but its skill charges up twice as fast.
Eunectes' Beacon.png
Can only be used in Acahuallan Jungle.
  • Passive: Ranged Operators gain a brief, stackable ATK buff whenever they damage an enemy.
  • Active: Taunts friendly units into attacking the Beacon, giving them a brief ASPD buff and SP each time it is hit. Will be returned to the Deployment Waiting Zone when retreated.
  • Directional EC Components
    • Block Wavelength: Reduces the movement speed of enemies in the Beacon's vicinity while in the Deployment Waiting Zone. Gives Transfer Permits and temporarily Slows enemies in the Beacon's vicinity when deployed.
    • Jam Wavelength: Amplifies the damage taken by unblocked enemies while in the Deployment Waiting Zone. Transfers a unit and inflicts a long-lasting, severe Fragile onto enemies in the Beacon's vicinity when deployed.
Tactical Equipment Toolbox.png
Can only be used in Mama John's New Plate.
  • Passive: Each Tactical Equipment of different classes buffs the Operator's ATK and automatic SP generation rate.
  • Active: Temporarily gives Operators a bonus Tactical Equipment of those they have.
  • Directional EC Components
    • Equipment Expansion Box: Increases the ATK and SP recovery rate buff.
    • Equipment Collection Box: Periodically generates DP and Transfer Permits for every Operator with at least 3 Tactical Equipments of different classes.
Portable First-aid Kit.png
Can only be used in Raythean Industries Test Platform.
  • Passive: Overhealed friendly units gain a stackable Physical/Arts damage-absorbing Barrier. Friendly units in a Medic's range periodically restores HP equal to half the Medic's ATK.
  • Active: Can transfer up to 2 out of 4 random Operators from the Preparation Area to give Medics one Tactical Equipment of the transferred Operator's class.
  • Directional EC Components
    • Efficiency Capsule: Friendly units healed actively restores SP.
    • Stimulation Shot: Friendly units healed actively gains a short-lasting ATK buff.
Energy Overflow Converter.png
Can only be used in Alsterii Bellariorum Manufacture Platform. Will always be in the Deployment Waiting Zone at the start of an operation.
  • Passive: Increases the ATK and ASPD of Operators for each enemy they are blocking.
  • Active: Gives Transfer Permits based on the total block count of deployed Operators.
  • Directional EC Components
    • Overclock Transformation Module: Increases the Transfer Permits given when the Energy Overflow Converter is deployed.
    • Energy Recovery Module: Melee Operators periodically restore SP for each enemy they are blocking (caps at 5).
Field Support Drone.png
Can only be used in The Abandoned Lighthouse.
  • Passive: Increases the ASPD of Operators on ranged tiles for every Operator within their range (self included).
  • Active: Loses HP over time (which is non-lethal) and heals nearby friendly units and removes Elemental Damage on them equal to a greater portion of the HP loss. Can be healed by friendly units and will be returned to the Deployment Waiting Zone when retreated.
  • Directional EC Components
    • Targeted Repair Formulation: Recovers 2 SP to friendlies whenever the Field Support Drone removes Elemental Damage on them.
    • Receptor Stimulation Formulation: Now also increases the ATK of Operators on ranged tiles for every Operator within their range (self included).


In the LT-3 operation, a Fleet-footed Thief, Shiny Pooloo, or Teary Detective will spawn as a "bonus" wave after breaks which do not deduct Life Points when entering a Protection Objective but awards one of three random Special EC Units of the player's choice; the game will be paused when the player is making the decision, which can be abandoned. Once obtained, the Special EC Unit will be in the Deployment Waiting Zone (unless no space is available, in which case it will be in the Preparation Area) and then can be used in all subsequent operations.

Special EC Units will no longer be available for the rest of an operation once deployed, so use them wisely.

EC Unit Use
Emergency Recall Box.png
Returns a deployed Operator to the Deployment Waiting Zone; the returned Operator keeps their Tactical Equipments and have their DP cost and redeployment time reduced.
Equipment Activation Valve.png
Gives 2 Tactical Equipments to a deployed Operator, which will be of their respective class. Does not affect on-deployment Tactical Equipments.
Preparation Area Transmitter.png
Can transfer up to 2 out of 4 random units in the Preparation Area.
Reassignment Transmitter.png
Can remove up to 2 out of 4 random units in the Preparation Area for the operation in return for Transfer Permits.
Recuperation Area Transmitter.png
Can transfer up to 2 out of 4 random units in the Recuperation Area.


Haywire EC Units are detrimental devices only given in the Emergency Resupply mode.

EC Unit Use
Heavy Insulated Concrete.png
Increases the DP cost of units in the Deployment Waiting Zone (including other Concretes but not itself) while in it. Can be deployed for a high DP cost but is invulnerable, does not obstruct enemies, and cannot be retreated — effectively rendering the tile it was on useless.
Shoddy Flashbang.png
Temporarily Stuns friendly units on ranged tiles when transferred, after which the Flashbang is taken to the Recuperation Area. Will never be in the Deployment Waiting Zone at the start of an operation.


  1. The in-game text omits this line, which can be misleading.

Changelog (Global)

  • March 16, 2023: Dispatch Cycle 3, "Southern"
  • November 16, 2023: Dispatch Cycle 2, "Recapture Land"
  • July 16, 2023: Dispatch Cycle 1, "Far West"
  • July 13, 2023: Rework II
    • Additional Special Bounty Area feature is now removed.
    • The reward cap is now doubled.
    • Reward and mission update intervals adjusted:
      • The Security Mission rewards are now reset every month as one Reward Cycle.
      • Every four Reward Cycles (4 months), the Dispatch Cycle changes where two new Security Missions are added.
    • Dispatch Missions added.
    • Emergency Resupply added.
    • Directional and Haywire EC Units introduced.
    • Security Missions are now made up of 6 operations (from 8).
      • Because of this, the bonus enemies will now spawn in LT-3 and only two of them that will appear (and only gives out up to 2 EC Units as the result).
    • The initial squad size is now 20 Operators (from 14).
    • Temporary Reinforcement is now only available after clearing the LT-1, LT-2, LT-4, and LT-5 operations, where the player chooses one of five Operators to add into the squad and has the option to forfeit the Reinforcement.
    • Operators shuffled at the start of an operation are now transferred into the Preparation Area (reverts the change in Rework I).
    • Danger Level effects now vary with the Security Mission.
  • Il Siracusano
    • Temporary Reinforcement Operator selection adjusted:
      • Two or more Operators with the same trait are no longer included, thus they will all have different traits.
      • No longer need to choose between the original or alternate version of an Operator when either is included. This also allows both the original and alternate versions of Operators to be present in the squad.
  • May 16, 2023
  • March 16, 2023
  • Dorothy's Vision: Rework I
    • Transferring Operators from the Preparation Area now costs 10 Transfer Permits which increases by 2 whenever Operators in the Recuperation Area are shuffled back to the Preparation Area, up to 20 (from 15 at all times).
    • 40 Transfer Permits are now given at the start of breaks (from 45).
    • Danger Level reworked:
      • Now rises every 50 seconds (from 45 seconds).
      • Each Danger Level now increases the HP and ATK/DEF of enemies by 25% and 5%, respectively (from 33% HP and 6% ATK/DEF).
      • The Danger Level now has varying caps depending on the operation and enemy wave (from having a cap of 50 at all times).
      • The Danger Level timer is now paused during breaks.
    • Supporter Tactical Equipment A's effect changed to "After deployment, gain 15 Transfer Permits" (from "After deployment, transfer 1 random Operator from the Preparation Area, and gain 5 Transfer Permits").
    • Operators shuffled at the start of an operation are now transferred into the Recuperation Area (instead of the Preparation Area).
    • Preferred Plan now prioritizes Operators with the highest promotion.
  • December 27, 2022 Introduced.