From CM-SS13
Evolves From: Spitter
Evolves To: N/A
Role: Bring the Hive's ranged combat castes to their maximum potential with long range acid glob shots, allowing you to bombard and heavily damage areas after a bit of setup. Use your enhanced vision to locate targets without being seen and shot. Use your acid lance for close range defense. Use your incredibly strong acid to make short work of everything in your way.
Guides: The Guardian Caste Guide

General Information

The Boiler is the evolved form of the Spitter and perhaps the ultimate ranged warrior of the Hive. It is a slow and weak large Alien with a somewhat weak attack, trading the Spitter's old role on the battlefield with a special, almost Support-like role. It is otherwise relatively average, with a decently large plasma pool that should not pose any issues, as the Boiler will typically be in the backline or midline of the xenomorph forces. It does, however, get the strongest Corrosive Acid in the game, making short work of anything the Boiler can physically get up close to.

With the unique ability to Bombard the battlefield with massive globs of acid and neurotoxin, the Boiler is akin to a mobile cannon, capable of standing back from the frontline and dealing immense damage to whatever is caught in its globs, or crippling and rendering vulnerable any host caught in its neurotoxin. Its acidic globs are capable of spreading four tiles from its impact source, and its neurotoxin is capable of spreading five tiles from its impact source; slowly consuming the battlefield with chemical destruction, and ending whatever is hit directly.

The Boiler is also blessed with enhanced vision, allowing it to zoom outwards in the direction it is facing. It is obviously critical for its role as a Support caste, and allows it to keep a small amount of distance from whatever it is bombarding. If it is ever caught at close range, it still has three last resort options; its acid spray, allowing it to instantly create a line of acid and deal large damage to anything hit, its acid shroud enabling it to create a defensive 'screen' of acidic gas, and its tail stab, injecting any target hit with acid and poisoning them from within.

Due to its high acid reserves, the Boiler also glows in the dark; allowing it to be easily seen by any marine.

Playing as a Boiler

With all of its abilities, it is patently obvious that the Boiler is meant to stand back and bombard its targets, often accompanying the majority of the Hive in their pushes or defensive holds. It is fairly common for them to set up at a distance from its targets, Beware that you will need an unobstructed line of fire between you and your target. Any solid structure will block your globs from impacting, although it is capable of travelling through other xenomorphs.

Once fired, you will fire a large glob of either neurotoxin or acid, that will hit any structure in its path. It has a high chance to be blocked by barricades when spreading, and will near-instantly kill anybody hit directly by the glob. It will then begin to slowly expand, reaching out four tiles for the acid and five tiles in total for the neurotoxin, counting the central tile.

Getting cornered at close range is a nightmare scenario - however, you still have tools to escape. Using your vision, speed, and weeds, you can attempt to escape before they get close, or use your acid spray to force the most aggressive to back off. If they continue pushing, your acid cloud can create a convenient smokescreen and prevent them from firing at you. Do not attempt to engage in melee combat if possible, due to your weak slashes and relatively low health. In the event you do die, however, you will explode into an acid cloud - as a final attempt to take the lives of your attackers.

Keep in mind you will take an additional 1.5x more damage against fire, however, despite your armor.


Abilities: Description:
Xeno Rest.png
Used to rest and get up. Xenos heal faster when resting on weeds.
To devour, grab a host with Ctrl + Click or

Grab intent (3 in hotkey mode) then click yourself, standstill. To stop the host from getting up and running away, you can switch to an empty hand (X in hotkey mode) and keep tackling them using Disarm intent (2 in hotkey mode) when you are devouring them. Xenos with devoured humans inside them can not vent crawl but Xenos with devoured monkeys can. Hosts with boot knives can injure the Xenomorph they are inside if they are conscious. (Edit this template)

Corrosive acid.png
Corrosive Acid
Vomit a glob of acid on item to dissolve it. Multiple items can be clicked at once as long as you are standing still. The cost of plasma is increased compared to other castes due to how the boiler has stronger corrosive acid.

Costs 200 plasma.

Brute Armour PASSIVE: Has a limited amount of armour to protect itself but takes 1.5 times the damage against fire.
Toggle Long Range Sight.png
Toggle Long Range Sight
Use "Stretch to fit" to minimize the hassle of changing icon size when zooming in/out.
Gives you a 4 tile view range boost in the direction you are facing, trading situational awareness for visibility.

Costs 20 plasma.

You dig in for 5 seconds and prepare to fire, firing either an acidic glob or neurotoxic glob. Your acidic globs will deal continual damage to anything caught in its radius, while neurotoxin will cause targets to suffocate, be slowed down and blinded, alongside eventually knocking them unconscious to be kidnapped.

Costs 200 Plasma, cooldown: 30 seconds.

Toggles Bombard Type.gif
Toggle Gas Type
Toggle between Acid or Neurotoxic gas types.

Acid Gas: Burns targets and barricades that linger in the gas cloud and knocks down targets directly hit with it while also dealing significant burn damage to them. The gas cloud has a 3 tile range.

Neurotoxic Gas: Suffocates targets that walk through the gas cloud and knocks down targets directly hit with it while also dealing significant oxygen damage to them. Has a chance to deal toxin damage. The gas cloud has a 4 tile range.

Costs 0 Plasma, cooldown: 0 seconds.

Spray Acid.png
Acid Spray
Instantly spray a line of acid out, extending 6 tiles and dealing high burn damage.

Costs 40 Plasma, cooldown: 8 seconds.

Acid Shroud.png
Acid Shroud
Create a small cloud of acid around you to cloak yourself. This will disable your other abilities for a short time to allow you to escape. Will also damage you as well.

Costs 0 Plasma, cooldown: 30 seconds on all abilities.

Tail Stab64x64.png
Tail Stab
Activating tail stab will begin a windup of one second, and upon conclusion, will enable you to launch a two tile attack that deals 1.2 times your maximum melee damage. It requires a direct click on the targets sprite, however, if it is missed, it only incurs a standard slash delay. Additionally, it will always hit the targeted limb. A Boilers tail stab will also inject 6 units of monomolecular acid, dealing consistent toxin damage and large amounts of pain to the target.

Unless otherwise stated, this is shared by all strains.

Cooldown: 10 seconds.

Attainable Strains



Strain Abilities
Abilities: Description:
Empower PASSIVE:

  • Deploy Traps is empowered by gaining 10 stacks of Insight. These stacks are acquired by hitting Acid Shotgun pellets, at a rate of 1 for 1. Hitting a target pointblank with the acid shotgun ability will give 10 stacks of insight, as well a hitting a rooted target with Acid Shotgun immediately gives 10 stacks. These stacks cannot go beyond 10, and are consumed upon casting Empowered Deploy Traps(will have a red arrow to show that it is empowered).
  • Acid Mine is empowered by casting empowered Deploy Traps.
Deploy Trap.png
Deploy Traps
Deploys a line of temporary resin traps that, when an enemy walks over, stuns them momentarily.

Stun Time

  • Default Deploy Traps: 1.75 seconds
  • Empowered Deploy Traps: 3 seconds

Casting Empowered Deploy Traps will empower the next Acid Mine ability.

Costs 60 Plasma, cooldown: 20 seconds.

Acid Mine.png
Acid Mine
PASSIVE: Hitting an Acid Mine shaves 4 seconds off the remaining Boiler Trap cooldown per hostile living mob hit.

Designate a tile in which a 3x3 acid mine will erupt. If anyone is in the 3x3 ranged acid mine, they'll be hit with acid.

Against Hostile Mobs:

  • Default Damage: 45 Burn
  • Empowered Damage If resisted: 30 Burn
  • Empowered Damage If not resisted: 51 Burn

Against Barricades:

  • Default Damage: 76.95
  • Empowered damage: 114.075

Costs 40 Plasma, cooldown: 6 seconds.

Acid Shotgun.png
Acid Shotgun
Launch a scatter shot of small acid blobs that fire damage enemies akin to spitter/praetorian spit.

PASSIVE: Targets restrained by traps take 75% increased damage.

Default Damage(Pointblank): 91.6 Burn

Costs 60 Plasma, cooldown: 15 seconds.

Toggle Long Range Sight.png
Toggle Long Range Sight
Use "Stretch to fit" to minimize the hassle of changing icon size when zooming in/out.
Toggles long range sight in the direction you're facing.

Costs 20 plasma.

Boiler Tactics

  • Never forget your strong acid. If you ever happen upon unprotected Marine positions, notably during a Marine retreat, your acid will melt straight through everything you can get your mouth on. Sometimes, you might be asked to open up flanks through reinforced walls too.
  • Always stick with your Hive, and make sure to be the first to fallback if your sisters are getting pushed back. You are not suited for frontline combat at all and any competent tallhost will make short work of you if they manage to get into range of you. Your Acid Lance is a desperation weapon, not an alternate fighting strategy.
  • Using a strong Tier 3 caste as a shield, preferably a Crusher in most cases or a Ravager or Queen if incendiary munitions are being used, will allow you to fire despite ongoing suppression. As long range weaponry, including scoped rifles, marksman rifles and sniper rifles, are your natural counter, you will find a shield useful in large fights, as you are a priority target for people using these weapons. Defenders make excellent shields as well, and it is generally easier to get a hold of one to guard you than a T3.
  • Expect to relocate often as the fight moves forwards and backwards. Your sweet spot will always be around 8 to 14 tiles, which is your aiming range when using Enhanced Vision. Of course, if you get shot at, you need to relocate much faster, especially if you are set on fire or don't have a shield.
  • As you are stationary, you are especially vulnerable to specific weapons with a long windup, notably orbital bombardments and CAS strikes. If you hear or suspect any of those, especially if you are surrounded by sisters, immediately relocate. You cannot survive such a strike if it lands straight on you.
  • Boiler gas usually makes good points for the Aliens to push, especially if aimed at non-fortified targets. Communicating your shots might help, especially if you coordinate with another strong pushing caste like a Crusher, or even a Queen.

Boiler Stats

Tier 16
Tier 15
Tier 14
Tier 13
Tier 12
Tier 11
Tier 10
Tier 9
Tier 8
Tier 7
Tier 6
Tier 5
Tier 4
Tier 3
Tier 2
Tier 1
Health Lower Melee Upper Melee Plasma Plasma Regeneration Armor Explosive Resistance Speed Evasion

You can learn more about alien stats here.