Chem Weapons
Chem weapons are any weapons that use chemicals (Either artificially or biologically) to break down organic or inorganic substances down to its basic, soupy elements. Basically, we are talking about acid here, the type that makes the Wicked Witch of the West scream, "I'm melting!". These weapons can also be derived from biological sources that rapidly accelerate decay, leaving whatever they touch as a mass of liquified, rotted flesh. Typically the most common user of Chem Weapons are Tyranids, but they basically have their own page for that. The other common user are the Death Guard, which is unsurprising given Nurgle's fondness for decay.
Chem Weapons are often used as a 'cleaner' counterpart to Flamers, as most chem acids are so powerful that the resultant victim is reduced to liquefied carbon composite that can be washed away with a spray of water. Furthermore, acids have the chance of weakening certain materials, which makes it great against power armor. Of course, that also means that certain materials can be so resistant to that particular acid compound that they can just laugh it off like water. Additionally, Chem Weapons just don't have the same psychological impact as Flamers as well as the fact that they don't have the unique aspects on sucking any breathable air in an enclosed space. Then again, nobody said that they can't combine the aspects of both....
Imperium
Chem-Thrower
A smaller version of the Chem Cannon. The Chem-Thrower is seldom used in the Imperial Guard due to the blowback affects that is notable for most chem weapons (The only reason why the Chem Cannon is used is because the Bane Wolf are front-line armoured units, far away from their comrades for the blowback to become problematic). However, for the hive gangs of Hive Worlds like Necromunda, nobody really gives a shit about safety procedures.
House Escher are the main users of the Chem-Thrower due to the fact that Escher deals with the manufacturing and export of drugs and other forms of chemicals. The Chem-Thrower is basically their rejected drug concoction that has been weaponised.
On tabletop, with Chem Alchemy it can become a fearsome, if expensive, weapon. It might be best to grab one of these mid-campaign when you know you can keep it effective with Elixirs. Otherwise it has the same caveat as a Flamer: keep it on a Specialist.
Chem Cannon
The main armament of the Bane Wolf, the Chem Cannon smother their targets in broiling clouds of noxious gas that dissolve organic material in moments. The victims' blood boils in their own veins and their flesh sloughs from one as the mixture of toxins do their horrific work before rendering even that down into a bubbling pool of rank, festering ooze.
Unfortunately, the acidic clouds of a Chem Cannon are known to drift according to wind direction, sometimes even back towards Imperial forces. So it is in the Commissar's responsibility to maintain at least a bag of chem resistant suits for his troops to survive.
In 8th Edition, Chem Cannon wounds everything that's not a vehicle on 2s, with an improved AP-3 (at the cost of range, only 8", and shot count, only 1d6 vs the Hellhound's 2d6). Between the wounding improvement and the AP improvement, this will outperform the Inferno Cannon against MEQ even before you account for its reduced cost - the range is the primary issue, as 8.1" charges will ignore it on Overwatch, and the secondary issue is that while it's obviously incredible against monsters and Primarchs especially, it's absolute garbage against vehicles, and utterly inferior to the Hellhound versus anything not MEQ or MC.
Chaos
Injector Pistol
Injector Pistols are the infamous weapon of Death Guard Biologus Putrifiers.
These weapons are only used on subjects the Putrifier wishes to study the effects of his latest strain of plague on and are often carefully selected among the enemy on the battlefield. They fire their Injector Pistols into vulnerable spots such as exposed flesh, chinks in armor and eye lenses before squeezing a concentrated dose of foulness into the target's body. A shot by an Injector Pistol injects a concentrated dose of Daemonic disease into the victim, causing him to erupt in explosive boils and clouds of flies.
Those specimens whose deaths are especially fascinating are pierced with injector pistols once again, this time to extract whatever clotted foulness now passes for their blood, ready for later study.
Bile Spewer
Technically not a flamer since it doesn't shoot fire but is still based on it. Papa Nurgle's forces doesn't use fire-based weapons because it doesn't leave anything for decay (since the flesh is burned off). Instead, his forces use "Bile Spewers", weapons using the flamer as the base weapon but the promethium tank is instead replaced with a tank full of toxic substances that does the same job as a flamer (efficiently kill infantry anywhere, be it in cover or in the open) but leaves a chance for the target's corpse to rot and decay, just as Papa Nurgle would like it.
Usually most players would swap the Bile Spewer for something better, but for a starting weapon, the Bile Spewer is a relatively decent weapon against horde armies and light to medium infantry. Even light vehicles aren't safe from this gun.
So far, this weapon's been only featured in Dawn of War II and is a great alternative to the Imperial Guard's Bane Wolf. It was later added in the Death Guard codex as the Plague Belcher; in this form, its statline is similar to a flamer but has one extra inch of range- a seemingly small change, but one that greatly improves its effectiveness in overwatch.
Plague Sprayer
AKA, the Nurglite Water Hose. A Plague Sprayer is the primary weapon of the abominable Plague Marines of the Death Guard Traitor Legion known as Foul Blightspawn. These cruel and malignant warriors take sick pleasure in watching their victims suffer in the grip of Nurgle's plagues.
On the field of battle, these foul servants of the Plague God spread putrescence and disease with their Plague Sprayers, which unleash a stream of stinking, infectious slime that is so potent that it can melt armor and flesh alike, rotting the souls of their unfortunate victims from within. The Plague Sprayer is attached to a contraption called the malignant churn, which the Blightspawn uses to mix and prepare his foul brew, stored in an "incubatum" worn on his back.
On the tabletop, the Plague Sprayer is a 9" Assault 1d6 S2d6 AP-3 D3 Plague Weapon that autohits like a flamer, which means that with a good enough roll for its S and number of shots it can trash anything from MEQs to vehicles.
If you want to go hunt monsters and tanks through making the most of his Plaguesprayer's high damage, than it is recommended to putt him near a Warlord with the Arch-Contaminator trait. You've got a 40% chance with T7 and a 68% chance with T8 to wound on 5s. Otherwise the Foul Blightspawn is best suited to take care of medium-to-low toughness units with multiple wounds, like Characters or Terminators.
Bile Spurt
The Bile Spurt is the literal orifice of the cutest little daemon engine you are gonna see, that has been modified and turned into a weapon to literally vomit its contents out. The stomach contents of a daemon engine, let alone one from Nurgle should already be considered hazardous as fuck to the highest order, so being drenched in one is gonna do quite a number on your body.
Do take note that the weapon is so obscure, that not even Lexicanum has a page for this. The only information we have on this thing is on its crunch as not even the Codex itself acknowledges this weapon's existence on its fluff.
Crunchwise, the Bile Spurt is a S6, AP-1, D1, Assault D3 Plague Weapon. It could kill GEQs and wound MEQs with some ease, however, it should be used more as a support weapon to help assist fellow Death Guard allies. Since it is literally a vomit weapon, its range is shot at 12", so you aren't hitting too far and should be reserved as a tertiary/emergency weapon just in case.
Plague Spewer
The Bile Spewer's bigger brother. Plague Spewers are a type of Plague Weapon used by followers of Nurgle such as the Death Guard. They are one of the primary weapons of the elite Blightlord Terminators, along with the Blight Launcher. They are pretty much the Nurglite equivalent to a Heavy Flamer.
In terms of crunch, the Plague Spewer is the same as the Plague Belcher but with heavy D6 S5 and AP-1. The plague equivalent of the heavy flamer. Stronger, but keep in mind that you still can't shoot it after advancing, which is pretty important given your slow movement. It also come at an ungodly price of 19pts.
Daemon Princes of Nurgle can now also bring a Plague Spewer, which makes up for not having a Warp Bolter, but still doesn't get Inexorable Advance, because Death Guard are bad at trait sharing; because the weapon automatically hits, this doesn't actually matter, but it's still massive derp.
Plaguespitter
Plaguespitters are the primary armament of the Foetid Bloat-Drone. Despite looking a lot like a Lascannon in appearance, the Plaguespitter functions in a completely different way.
Not much is completely known about the Plaguespitter other than the fact that its name heavily alludes that it fires off like a machinegun rather than the pinpoint accuracy of a Lascannon. Furthermore, it could be assumed that the bullets or projectile it fires are drenched in disease and corrosive chemicals. This is supported by the fact that the Plaguespitter functions a lot like a Pus Cannon, in that it uses the mashed remains of flesh-mower victims for excellent fuel. So in a sense, this gun fires projectiles made up of your dead and rotting friends. How pleasant.
The above is now officially more or less confirmed. As the Bloat-drone or Plagueburst Crawlers slurps up diseased innards and maggot-thick mud through its strange metallic cables until its flesh starts to strains and pulsates, refining a hideous cocktail of hyper-concentrated toxic slime. Then, with a sudden spasm of regurgitation, the drone or Crawler squirts the resultant soup through its Plaguespitters, spraying it in great fans across the foe.
On tabletop, the Plaguespitter is an assault D6, S6 weapon that can re-roll 1 to wound, making it quite the threat to normal infantry.
Blight Launcher
Blight Launchers are a type of heavy Grenade Launcher used by Death Guard Blightlord Terminators and Plague Marines. This, along with the Plague Spewer is one of the primary range weapons of the Blightlords.
Blight Launchers are basically the Nurglite version of Plasma Cannons as it primarily fucks up most types of infantry. As Plasma Cannons vaporize any disease upon impact, the Blight Launcher acts as a compensation for Papa Nurgle; hitting with roughly the same force as a Plasma Cannon whilst leaving a pool of toxic chemicals in which Papa Nurgle loves the best. How considerate of Nurgle.
In terms of crunch, they are 24" Assault 2 S6 AP-2 D d3 plague weapons. A hard-hitting anti-infantry weapon that's also good against light vehicles. It can very well substitute plasma weapons if you want some more range in exchange with AP. It also has some really nice combo with Arch Contaminator. Now four points cheaper thanks to Chapter Approved!
Heavy Blight Launcher
Take three normal Blight Launchers, duct taped them into a symbol of Nurgle and then supercharged that motherfucker. A Heavy Blight Launcher is a type of heavy Grenade Launcher used by the forces of the Death Guard Traitor Legion.
This ugly piece of daemonic tech is capable of firing three armor-piercing blight shells at a time drawn from a rusting drum magazine in rippling volleys. This rain of disease-ridden shells can reduce a battle tank to a corroded, collapsing wreck in moments, or bring whole squads of heavily armored infantry such as Terminators to their knees.
Furthermore, the Heavy Blight Launcher have a much more higher rate of fire than the regular Blight Launcher, enabling to sustain a consistent volley of weaponized space herpes at the enemy. Hence, it acts more of a anti-tank weapon than a light artillery.
On tabletop, Heavy Blight Launchers are basically three normal Blight Launchers with 12" more range; considering that it's got a 4+ to hit, and can't get Inexorable Advance. This may seem like a mediocre option at best, but in practice, it is actually a lot better than you'd think. 8th edition has many, many fast moving assault armies and plenty of units that can charge out of deepstrike to be on top of your fire support elements in the blink of an eye. Whilst other Death Guard units are too slow to react, move and counterattack a wide form of lightning bruisers like Assault Marines, Helldrakes and Flyrants; enter the Bloat Drone. The Plaguespitters are great, but if you need some long range fire support that can't get tied up by enemy assaults, the Heavy Blight Launcher has you covered. It can fly, its (important) stats don't go down as it takes damage, it's tough as nails for its cost, and it can play keep away with assault elements in the enemy army without sacrificing its usefulness.
Plagueburst Mortar
The quintessential Chem artillery. The Plagueburst Mortar is the primary weapon of the Plagueburst Crawler, a Daemon Engine that provides mobile artillery support to the Death Guard. These Plagueburst Mortars boast a parabolic fire arc and very good range, while the shells they fire combine high-radius explosives with lethal clouds of corrosive daemonic spores to inflict damage comparable to that of Imperial Demolisher Cannons. The drawback of this weapon is its inability to fire at targets that are closer than its minimum range. Every shot spreads billowing clouds of lethal spores amidst shock waves of fire and shrapnel.
An area under sustained bombardment from these weapons can become so saturated with these spore clouds that it would become for all intents and purposes, unable to support life again. Seriously, not even the rotting lifeforms of Nurgle could survive these clouds, these shells are baller as fuck. Daaaammmnnnn, these things make a Virus Bomb look as inept as a firecracker.
Because of such extreme chemical affects. Armor provides scant protection, as these spores somehow chew through ventilator grills and enviro-seals, corrode the thickest adamantium plating, and wear through rockcrete layer by layer until they spill into even the deepest and most well-protected bunkers. These effects have made the Plagueburst Crawler a much-hated weapon of war. Enemies strive to destroy them at any cost, while even the daemons of Nurgle look at them askance. After all, where the Plagueburst Crawlers strike, there can be no cycle of rebirth, no matter how foul. If all this sounds super Edgy to you, its because it is. Its creator is Ol' Morty himself, a weapon clearly crafted from the sheer bitterness of the Daemon Primarch.
On tabletop, the mortar is Heavy D6, S8, AP-2, Dd6 and can shoot at targets 12"-48" away, even if it cannot see them and it's also a Plague Weapon.
Rot Cannon
The Rot Cannon is a large weapon similar in size to a Battle Cannon used by Imperial main battle tanks. The Rot Cannon is carried into battle by Plague Hulk Daemon Engines used by the Forces of Chaos.
The weapon is an arcane device of unknown, although possibly obviously daemonic origin and is fused to the end of the creature's right arm. The Rot Cannon belches out shells that are so impregnated with dark ichor and infection that a mere scratch from the weapon's bone fragments will immediately and agonizingly fester into a crippling injury.
The Plague Hulk itself is a lumbering brute of rotting meat and metal, but its slow speed and large size means that it can't really afford to charge through an open battlefield even with its crazy Nurglite resilience. A battery of Basilisks Earthshaker Cannons can do a number on you, no matter how tough. Hence, the need for a Plague Hulk to have a range weapon such as the Rot Cannon is of much importance.
In 8th Edition, the Rot Cannon is largely unchanged but with new stats, 36" Heavy D6, S6 AP-3 D2 and all wound against Infantry are rerolled (cool).
Pus Cannon
The biggest chem weapon to date short of Virus Bombs. The Pus Cannon is a disgusting weapon (And we mean disgusting, just look at the fucking thing) made up of a biological tube mounted in a normal gun turret. This weapon is fed by two large rendering vats full of rancid lard and rotten meat. The Pus cannon fires a gob of this vile goo at the enemy. Those who aren't drowned in filth fall ill, and promptly die from a deadly bacterial infection. It is mounted on the Nurgle Plaguereaper, a possessed Baneblade but could also be found on the Contagion and Nurgle Plague Tower. However, the latter two daemon engines are fixed mounted to the front, reducing the weapon's true capabilities.
Like the smaller Plaguespitter, the Pus Cannon's ammunition refill works via dumping as much dead bodies in its two septic tanks as possible. The bodies then liquefy into a soupy goop of pure nasty before being discharged into the weapon's barrel.
Due to the fact that the Pus Cannon looks like a dick with severe space genital warts and that it, for all intents and purposes, ejaculate its thick, slimy juices at people. It is pretty flabbergasting that this phallic shit was not part of a Slaaneshi armory instead.
Dark Eldar
Liquifier Gun
In simpler terms, they are the Dark Eldar's version of a Bile Spewer. More specifically however, Liquifier Guns are Dark Eldar weapons which spray a huge amount of potent acid that melt through body and armor alike. Minions of feared Haemonculi usually have built-in liquifier guns attached to their arms and by extention, their heavily mutagenic bloodstream from which they can fire their own acid-like blood onto the enemies.
Just as its name implies, Liquifier Guns reduce biological and inorganic materials into a chemical soup as the chemicals within these weapons are so potent (Thanks to the advancement in biological and chemical technology of the Dark Eldar) that very few factions can rival it.
In terms of crunch, Liquifier Guns is a D6 weapon that auto-hits with AP-D3. Even the worst roll for the AP still screws with armor and that 33% chance of turning power armour into a 6+ save is fantastic. Unfortunately it only has the strength of 3.
Destructor
The Destructor is a Dark Eldar weapon used primarily by Haemonculi. It resembles a long tube, with a cavity to slip one's hand into up to the elbow. The ammunition for the weapon is carried in a small container the Haemonculus wears, fed through a series of tubes. The Destructor sprays a wide stream of an incredibly corrosive organo-acidic compound when fired. This toxin can eat through any known armour, burn flesh, and once inside the target's system can cause, "blood vessel explosion or implosion; pharyngeal contraction; extensive haemolysis; skeletal disintegration; sclerotic corrosion; intercostal spasms; hyper-reacted thermoreceptors and chemoreceptors; Eustachian damage; retinal scarring; cardiac and respiratory atrophy and aqueous humor deprivation."
This device's effectiveness in combat has been confirmed time and again, with reports of a single Haemonculus able to decimate an entire squad of Space Marines with a single well-aimed volley, every man among them dying from sheer pain, or worse, leaving them alive but immobilized - blind, hideously burned, hemorrhaging blood from every orifice, wracked in unimaginable amounts of agony, helpless and in the twisted hands of the Haemonculi.