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Understanding the Key heroes[]

Before you look at any teams, you should learn a basic technique which is used throughout this guide. This involves the use of Serial, Kurtz and Flatline; understanding how this trio works is vital to extreme campaign success.


Serial is the key to extreme, it is possible to complete some missions without him in the early districts, but it is unlikely you will get far. His skills are essential for completing the missions. This is unfortunate as he is a 7* hero and a lot of players won't unlock him for a long, long time through Alliance Wars and have to rely on pure chance he will be unlocked through a hero crate.

Reactive iridium armour[]

Serial - Reactive Iridium Armour.jpg

This is the single-most-useful skill in the game for extreme, in the extreme campaign, enemies are strong and they are significantly over levelled compared to you, this means they have more health and deal more damage than you. Serial's reactive iridium armour is commonly referred to as his shield, it is invincible and no enemy can do damage to serial while it is active. On top of this, it taunts all enemies so your team members won't be shot at while this shield is active, this makes his shield even more deadly as well because when the shield ends, it shoots off and targets an enemy at random. As explained in the skill box, 75% of all damage this shield receives is reflected back into a single enemy when the shield ends, this means when the shield is up you want to be shooting at enemies and soaking up damage.

Hot swap[]

Serial - Hot Swap.jpg

Hot Swap has a single use, it is saved until Serial's shield is ending and then hot swap is used to charge his shield back up instantly. This skill puts 61 rounds into Serial's weapon and increases the fire rate by 60% meaning he shoots faster and the bullets also do more damage. Make sure not to reload until every bullet has been used however or you will lose the skill buffs. This skill should always be saved when it charges, only ever use it when you need to chare his bronze skill up.

Oppressive fire[]

Serial - Oppressive Fire.jpg

This skill can be very useful when it is triggered, oppressive fire doesn't only reduce fire and reload rate but it also staggers enemies, this is important in extreme missions where a stagger can stop an enemy from doing a skill that may kill a team member. However it is triggered by critical hits only and that is entirely random, it is useful when it happens but cannot be relied on.


Kurtz is used in a lot of teams from District 1 to District 3, this makes him a vital hero that is essential to beating extreme missions. Just like Serial, a lot of players don't have Kurtz because he is a 7* hero and can only be unlocked through crates or the Alliance Wars Season rewards. All of Kurtz' skills are vital to completing missions as they synergise well with flatline and hivemind, but in order to succeed in the extreme campaign you need to understand how the skills actually work. In this case, all 4 skills are useful.


This skill has one use in extreme and one use only, it disorients enemies so they can’t shoot at you very well. In extreme the level of the enemies will always be higher than your level meaning you will not be able to dominate them. But you can disorient no matter the level, this is important as it can be done to a main damage dealing enemy such as Astrix or Siren.


Execute is the single-most useful skill for the first 3 districts in extreme, as mentioned previously, you cannot dominate your enemy so you will execute your own team member as a result. This means you will need a revive hero such as Flatline in order to 3* a mission. Execute is so powerful because it increases the health pool of your team greatly and also increases their damage, this is how you can defeat the over-levelled enemies in most missions. Remember that the team member who is executed won’t receive these buffs however, so when they are revived there is a chance they will immediately die again. This can be countered by timing the skill with Serial’s shield or you can use Mandrake to cloak the weakened enemy, this won’t last for long however.

Ruthless leader[]

Ruthless leader is why you don’t need a healer in a lot of early extreme missions. As mentioned above, when you execute your team member the remaining team members alive will receive a massive boost to health and damage as explained above. Ruthless leader adds a boost of healing on top when you execute, this means if your team is all running low on health then they will suddenly be full health with the execute buffs.

Fierce Retaliation[]

Fierce retaliation is the skill everyone hates in PVP because is heal blocks you and does continual damage, when combined with Halo, Krieger or Kiyoshi it also triggers their passive damage so you are taking even more damage. This skill does a massive amount of damage to enemies, for some missions it is advised to take Halo or Kiyoshi with you to do that extra damage on top. This skill is especially useful as well because it is triggered when you lose a team member, this means you can execute your own team member, get the buffs and trigger damage to all enemies on the field. It is also triggered by drone spawns being destroyed, such as Hivemind and Striker’s drones, this is useful as Hivemind’s drones taunt enemies meaning it is destroyed often triggering this extra damage.


Flatline is the other side of Kurtz that needs to work in order to complete extreme missions flawlessly, similar to Kurtz all her skills are useful here but her Silver "Taser" is self explanatory, it stuns enemies up to 6 seconds. To use Kurtz properly, you need to execute your own team members, Flatline can revive the executed team member meaning you can get 3* for the missions as long as you revive them before the mission ends!


Clear does exactly what the skill says it does, it revives a fallen team member. In this case it will be the team member Kurtz executed. However beware if Flatline has low health then she may end up killing herself using this skill, this means you will be unable to revive again during this run and will get a maximum of 2* for the mission. It is important to note that Kurtz may execute flatline as well.

Stay with me[]

Stay with me brings a team member back from the edge of death when they receive fatal damage, this can be especially useful if you are struggling to get Serial's shield up and take fatal damage, if you have Mandrake on your team then the passive heal from his gold skill "Survival Instincts" cloaks the dying team member and stacks a heal on top of Flatline's. This skill only applies to characters and Flatline won't revive drones or turrets from near death.


This is a strange skill as sometimes it is triggered and some times it is not, if an allied team member is killed and this skill is still building then it will apply the 20% boost to the cooldown, sometimes drones can trigger this as well. But if you have just used Flatline's "Clear" skill and a team member dies with the cooldown at near 0, then she will not receive this platinum 20% boost. This skill is vital to the timing of Kurtz' execute as when he executes and enemy, this skill boosts Flatline's revive and she can revive the executed team member faster.


Serial, Kurtz and Flatline synergise together well if you can time their skills. When you start a mission you should always be using Serial to try and build up his bronze skill, this invincible shield taunts all enemies and takes the damage off your team members. When you use his shield, switch to Kurtz, if you are too slow then the friendly AI will use Kurtz' dominate skill, this is when flatline will use her Taser, this is important because Execute has not charged up yet but Flatline's revive will have. You need to make sure you do not shoot and kill the enemy that Flatline is stunning as this will cancel her taser and her AI will use her revive before execute has been used.

If you time this right then the steps should be simple and efficient:

  1. Use Serial's shield.
  2. Swap to Kurtz and wait, don't do anything until Execute charges up.
  3. Execute then swap to Flatline (she should still be tasering), roll to cancel her taser.
  4. Revive then swap back to Serial, his shield should last roughly 5 more seconds but his AI will have used his silver skill "Hot swap"
  5. Use serial's extended clip to shoot an enemy and build his shield up instantly giving you time to take out the enemies.

If you were too slow or killed Flatline's stunned enemy then the AI will automatically use her revive, you can tell if she is using her skill by looking at the below image.

This image shows Serial was executed and the rest of the team received the buff, in some cases this is ideal as serial can use his Bronze skill which produces an impenetrable shield. This means he will take 0 damage while the shield is up. However for this to work effectively you need to ensure serial does not use his shield before being executed, this means when he is revived his shield is charged and ready to be used. This can be very hard to do and it is recommended you change up your line-up to stop Kurtz from executing Serial. Below is an example of how a Kurtz, Flatline and Serial team works well together even when Serial get's executed, if you don't want him to execute Serial then I would recommend scrolling down to this section which explains how to stop Kurtz executing a specific hero.

Skill Saving techniques[]

In order to beat extreme with 3* and minimal frustration it is recommended you learn how to use Serial efficiently and effectively. As explained above, his skills are self explanatory and we mainly use him for his invincible shield and high damage. What most players don't realise is his silver skill "Hot swap" can instantly charge his shield from 0% to 100% if every bullet lands, if you don't use all the 61 bullets and the wave ends then he also starts a new wave with a full 61 capacity. You can see this in the below video where I use Serial efficiently and Kurtz' execute was not even needed.

I would recommend watching the video and then reading this. I explain what I did and why I did it, learning to do this is vital for extreme district 4 and 5 which don’t make use of Kurtz in a lot of teams, you have to rely on your skill using Serial and your understanding of their skills.

I made sure to kill the weaker enemies first and leave Alvarez and Heim alive, this means the shield will hit one of these two enemies effectively instantly killing them. At 20 seconds after the shield kills Alvarez you see I don’t go full auto on Heimlock, I do short bursts which charge up Serial’s shield without killing him and allowing him to heal, this is done to build the shield before the next wave begins.

At 28 seconds you will see I use Serial's silver skill "Hot swap" to finish building serials shield before Heimlock dies, but I don’t use all the ammo in the clip and don’t reload. At 38 seconds you can see the second wave begins and I have a full clip as well as a full shield ready to go, I identify Astrix as the main threat and kill her first. Then at 1 minute you see I repeat the same technique to build serial’s shield before the next wave and I start the next wave by using the shield, you will see my silver skill is charged again, this should be saved until Serial’s shield is about to end as using his silver you can build another shield almost instantly.

Kurtz is executing my Flatline, what do I do?[]

As mentioned above, Kurtz is great for what he can do but if he executes your Flatline you will get a maximum of 2* on the mission so you can't quick win it later. This can be solved fairly easily despite his skill description saying he "Executes the weakest allied hero, immediately killing them" when it doesn't define what the "weakest" hero is seems to execute at random. This can be seen in the two teams below which are identical in every way, except in one team Kurtz will execute Flatline and in the other, Kurtz executes Hivemind.

Kurtz Executes Flatline or Hivemind.jpg

This can easily be avoided by changing the team order, the execute skill seems to function based on where Kurtz is placed in the team. When you are selecting heroes, you have 5 slots to choose from. In this screenshot, Flatline was moved to slot 1 and Kurtz was moved to slot 4, this stopped him from executing her, however this is not a universal rule. If you are finding Kurtz is executing Serial instead now and you want to keep him alive then do some more moving around until he executes a hero such as Mandrake or Hivemind, the main heroes you need to keep alive are Flatline and Serial.

You may run one of the teams stated in the guide in the exact order it is shown, but you will find Kurtz still executes your Flatline or Serial where he did not for me. This is because every player has their heroes levels up to different stages, in this example moving Kurtz and Flatline worked but for you it may require experimentation. It is recommended you try the team order shown in screenshots first and then begin moving the order if it does not work. You can see in the below video that I had to quit and restart the mission to rearrange the order, because of this, it is recommended you use Kurtz' execute in Wave 1 to see which hero he executes, you don't want to restart the mission when you have nearly completed it!