"Relaaaaax. I'll invent new stuff. Like... spider robots with daemons in, and they have claws and stuff. They'll defile things. Maybe they can be called Defilotrons. It'll be sweet. And they'll have a gun on their chests, and tiny little heads. What? Why are you looking at me like that? You just wait. We'll rock this place all to hell."
The Chaos Space Marines don't have a lot of their own vehicles at their disposal; whilst the loyalists have all kinds of nifty-cool tools fresh out of the Adeptus Mechanicus' foundries, the Chaos Marines have to make do with equipment that is antiquated in contrast. In many cases, their technology is capable of bridging the gap; the Chaos Marines field a number of weapons no longer in use with the Astartes (man-portable autocannons, for example). In other cases, their technology is inferior; the Chaos legions lack anything resembling Landspeeders, Whirlwinds, or Razorbacks, for example.
But it's not all bad. Chaos Space Marines are nothing if not inventive. And thus they came up with a vehicle that is as horrifying to look at as to be attacked by - the Defiler.
Often jokingly called a giant enemy crab, the Defiler was supposedly first conceived by Failbaddon, which would make it one of his only successes, but its true origins are tacitly believed to lie with the Word Bearers. The Defiler was made to provide Chaos Marine forces with a legitimate alternative to Dreadnoughts for close support; historically, Chaos dreadnoughts were made with older and less-perfected tech, ensuring that every single moment that the pilot was installed in his sarcophagus, he was set alight with horrifying agony. This generally results in Chaos Dreadnoughts having outbursts of pain-and-rage-induced Hulk Syndrome and fucking up every goddamned thing in sight.
Suffice to say, this was proving problematic, and the Chaos marines sought a new way to get close-support that was less-likely to say, fire off a Plasma Cannon at its squadmates in a fit of rage over them not turning down the fucking Pat Benetar when the Dread's pilot has a headache. The answer came in an unexpected way - a Daemonically-Possessed machine with no actual crew, bound with rune-inscribed wards and sworn to obey its master. Whilst many daemons are driven halfway-mad by their imprisonment within the engine, the Defiler's occupant gets its head in the game when combat starts, showing blind loyalty to its master - and relishing in its power to blow things up and make shit dead (or re-dead in the case of the Crons).
As a possessed machine, it is completely fearless; destroying the Defiler will free the daemonic essence trapped in the machine, so whether it runs around killing things or gets destroyed by a Meltagun blast, the Defiler is kind of win-win for its occupant. Indeed, when a Defiler is destroyed, its pieces are often refurbished by the dark gods to create new bodies for the fiends that combine both daemon-flesh and mechanical components, known as Soul Grinders.
The Defiler is a powerful beast. By default it's got as much armor as a Dreadnought, has 2
Dreadnought Close-Combat weapons power fists, a Battle Cannon, a Reaper Autocannon, and a Heavy Flamer - quite a bundle of weapons for both close-combat and ranged assaults. Even better, it's highly upgradeable - the Reaper Autocannon can be replaced with a Twin-Linked Heavy Bolter (for shredding infantry) or Twin-Linked Lascannon (for vehicle-busting). It can also exchange its Heavy Flamer for a Havoc Launcher, enabling it to launch reasonably-effective frag missiles out to a long distance for additional fire-support. Additionally, you can tack a second Havoc Launcher on the side to flick some extra rockets. To make it even better it's been given Daemonic Possession, which means it's almost immune to Crew Shaken/Crew Stunned results, and has a 5+ invulnerable save. Topping it all off, it has solid armor (AV 12 front and side armor), with only its rear armor being a vulnerable point (AV 10) and 4 hull points, giving it some pretty decent staying power.
Alternately, it can exchange the Reaper Autocannon for an additional power fist, giving it +1 attack for each, and giving it a walloping 5 attacks on-the-charge. He also can exchange Heavy Flamers for power scourge, which could add another +1A (if you chose to use it's profile instead of fist - its "only" S8 compared to the fists S10), and also lowers the WS of enemy models in BtB contact, which is cool, considering Defilers own pathetic WS3. Paired with the fact that it has Fleet, this makes the Defiler capable of causing serious damage to anything unfortunate enough to get caught up in its crabby claws, especially commander units and vehicles.
Whether you use it as a shooty walker, a melee-only walker, or some blend between the two (it can easily pull double-duty), the
Giant Enemy Crab Defiler is guaranteed to be a giant fire-magnet, and enemies will devote truly retarded amounts of weaponry in an effort to hit its weak-point for massive damage. Unless they have a Lascannon type weapon, then they just one shot the damned thing, since it's not hard to land a shot on the back from far enough away.
In its standard configuration, it is good at every task but it doesn't exactly excel at any of them. It will lose out if made to compete against a more specialized vehicle of its size. So it will be outdone at long and medium range by a hellfire dreadnought, out-artillery'd by a basilisk or whirlwind, and out-melee'd by a crushing claw carnifex or pair of deffdread (you can field two with 4 DCCW's and riggers for exactly same points). But it makes up for this by being able to perform just about every needed task with the exception of anti-air duty, and if it has Twin-Linked Autocannons or Lascannons even this is debatable, though the lack of the anti-air rule hurts quite a bit. Mind, when dealing with actual Forge World-made aircraft, a Havoc Squad full of Autocannons or Flak Missile Launchers is usually the best option for the points, since Chaos lacks any dedicated anti-air vehicles, heldrake notwithstanding.
The Defiler is a mighty vehicle and in all seriousness one of the overall most-flexible options Chaos has; it's as ubiquitous for the traitor legions as the Leman Russ is for the Imperial Guard. However, the Defiler has a number of very notable drawbacks on the tabletop. First and foremost, it's a very big vehicle, and a very obvious one at that - the model is roughly as long as a Land Raider and a lot taller, and this means Ordnance and blast weapons are less-likely to miss the damned thing. It also means that its vulnerable side (its back) is much larger than those of other vehicles.
Secondly, the Defiler's being Demonically possessed means its WS and BS are only 3 - average at best compared to the good accuracy of most Marine units and vehicles. Whilst every non-battle cannon weapon the Defiler can mount is twin-linked (ergo reducing the problems it may have with accuracy), the close-combat weapons it has are not so fortunate, causing the Defiler to rely on volume and sheer force to damage enemies in close-combat (it will miss about half the time on average, but will fuck up whatever it hits when it does).
Thirdly, the Defiler, due to its very large size and middling accuracy, is surprisingly vulnerable to being Tarpitted. This is because even with its considerable melee punch and fleet, it is particularly large and vulnerable to being tied up by expendable dick units like Conscript Squads
(especially if they're used by a certain general who can replace them for free), Termagaunts, Scarabs, or Kroot which force it to spend valuable time mulching them as opposed to doing its valued job of raping vehicles and commander units. Take care to make sure that the Defiler is kept out of melee range of tarpits unless it's actively trying to get stuck in or it has melee support that can clear the way. With those new Necron Scarab rules, you should probably definitely avoid leaving your Defiler anywhere near a horde of those little vehicle-eating buggers. Also, if it meets a terminator squad with a chainfist or two it's probably going to get its shit pushed in. Hammernators can also take it down over the course of a couple of turns - but if it does engage them, it will actually be keeping them from hammering the rest of the army to bits.
Fourthly, it has awful armor, at least for the cost. No really, 12/12/10 is just crappy for a 195+ points vehicle, especially in this day and age. Even with 4 hull points and a 5++ save an enemy with moderate firepower can down the thing in a single turn without focusing much firepower on it. Also because the battle cannon is ordnance so if you actually do use it the other guns you put on it will be shooting at BS1; making them of very dubious usefulness. And you didn't spend 195 points for a poor man's Leman Russ battletank that's a bigger target, can't be taken in squads, much more fragile, and significantly more expensive. Its ranged firepower is also very...schizophrenic to be charitable. Even disregarding the effects using the battlecannon will have on your accuracy; the heavy flamer is an extremely short ranged weapon meant to kill infantry; the Battle cannon is a long ranged weapon optimized for killing MEQs and the reaper autocannon is a mid ranged weapon meant to kill light vehicles (though with two shots at 195 points you're probably better off investing in a forgefiend). What's worse is that you can't really make the ranged weapon loadout more focused since your options to replace the heavy flamer is a havoc launcher; though swapping out the autocannon for a lascannon isn't the best build either (again, you'd be paying 195 pts for one shot). The most "focused" ranged build would have the havoc launcher and heavy bolters to maximize on mulching infantry but at the end of the day, for the price you're paying it's still not very stellar anti-infantry firepower.
The Defiler's ranged firepower is extremely weak for a model of its size, fragility, and points cost the current meta having been left far behind by power creep. If you're just using the battle cannon, you are paying far more points for something that the Imperial Guard can have three of per heavy support slot from a platform more effectively able to use it that's also more compact (and thus easier to hide) and has AV14. This is a terrible usage of your points and the Battle Cannon is not particularly stellar to begin with, being at best "okay" against vehicles and in a meta with cover and invulnerable saves out the ass everywhere you'll get pretty disappointing results shooting against infantry. The other guns can't really be used with the battle cannon due to the ordnance rules, and if you're just using them you're paying a ton of points for very little dakka. In melee, the Defiler is let down by bad WS, most of the things that the Defiler would want to be in assault with either being able to zip away before the Defiler can ever touch it, being able to tar pit it with sheer numbers, can reduce it to dust with haywire grenade spam, or would strike first with what is quite possibly a D-strength or Armorbane weapon and promptly punch the Defiler's head straight out its ass. Defilers are not a waste of your heavy support slot, but it is best to wait until the next codex and hope that someone in GW decides they need to sell more defilers and give them 6e wave serpent esque buffs.
8th Ed brings with it much needed changes for the Defiler that are probably going to improve it a lot. Under the new vehicle rules it has 14 Wounds, Toughness 7 and 3+/5++ armour save, putting it around a Leman Russ in survivability (Lemanators have T8 but 12 Wounds), and can move 8", not bad for an enormous angry space crab. Changes to twin-linked and template weapons are also going to help. Twin-linked has changed in that it's been removed, so now all twin weapons are just two of those weapons. With templates gone, Twin Heavy Flamers have 2D6 attacks, all of which auto-hit. Literally you'll be able to insta-scorch entire squads of dudes and then, because units can now fire all their weapons AND fire them at different targets entirely, you can lay waste to some other shit with your other weapons, and they'll be -1 to hit instead of snap firing.
The Defiler's options now include being able to replace the Twin Heavy Flamers with a Havoc Launcher or a Defiler Scourge, and replacing the Reaper Autocannon with Twin Heavy Bolters or twin Lascannons. This gives the Defiler some really good flexibility to deal with almost anything it can face. The Havoc Launcher really is shit but the Defiler Scourge now lets you deal three additional S12 attacks dealing 3 damage each, while the Defiler Claws now hit at Strength 16 and do D6 damage each, giving it a good defense against MC or Terminator tarpits, while rocking Heavy Bolters and Heavy Flamers will lead to hilarious RAGE from swarm players who try to charge it. Of course, changes to 8th now effectively negate tarpitting as any unit can simply walk out of combat, requiring your opponent to repeatedly get hit with a ton of heavy flamer attacks every turn if they want to keep it tied down.
A Slaaneshi Defiler from 3rd Edition, back when they were able to mount Doom Sirens and Blastmasters.
|Forces of the Death Guard|
|Leaders:|| Chaos Lord - Daemon Prince - Sorcerer - Chaos Champion |
Malignant Plaguecaster - Plague Surgeon - Tallymen
|Troops:|| Biologus Putrifier - Blightlord Terminator - Chaos Spawn - Deathshroud |
Foul Blightspawn - Noxious Blightbringer - Plague Marines - Possessed
|Vehicles:||Chaos Land Raider - Helbrute - Plaguereaper - Predator - Rhino|
|Flyers:||Storm Eagle - Stormbird - Thunderhawk|
| Blight Drone - Defiler - Foetid Bloat-Drone |
Myphitic Blight-Hauler - Plague Hulk - Plagueburst Crawler
|Daemons:||Beast of Nurgle - Nurgling - Plaguebearer|
|Auxiliaries:||Cultists - Pestigors - Plague Zombie - Poxwalkers|
|Allies:||Chaos Daemons - Chaos Space Marines|
|Forces of the Thousand Sons|
|Leaders:|| Chaos Champion - Chaos Lord - Chaos Sorcerer |
Daemon Prince - Exalted Sorcerers
|Troops:||Chaos Spawn - Rubric Marines - Rubric Terminators|
|Castellax-Achea Class Battle-Automata|
|Vehicles:|| Chaos Dreadnought - Chaos Land Raider |
Helbrute - Predator - Rhino - Vindicator
| Silver Tower of Tzeentch - Forgefiend |
Heldrake - Maulerfiend - Defiler
Fire Lord - Doom Wing
|Daemons:|| Flamers of Tzeentch - Horror - Screamers of Tzeentch |
Mutalith Vortex Beast
|Auxiliaries:|| Cultists - Prospero Spireguard - Thrall Wizards |
Tzaangors - Tzaangor Enlightened - Tzaangor Shaman
|Allies:||Chaos Daemons - Chaos Space Marines|
Elsewhere on /tg/
The Defiler is also the name of a Wizard variant class/kit from the Advanced Dungeons & Dragons setting of Dark Sun. Long story short, on Athas, magic was developed when some dick learned how to tap into the life energy of the planet and convert that into mystical power - before then, everyone used psionics. It promptly took off like wildfire - fittingly, since ripping life out of the earth itself tended to fuck things over for plants. You see the shithole that Athas is now? That's the result of rampant overusage of defiling magic.
In AD&D, Defilers were more powerful than vanilla wizards (who also existed in the setting as Preservers, carefully taking only what energy they needed for a spell instead of just ripping it out wholesale), mostly in that they gained levels a hell of a lot faster. The downside was that they killed everything around them when they used spells, which on a dying planet made them Public Enemy #1.
Defiling became a general option for all Arcane classes in 4th edition, where they could beef up Daily Spells at the cost of killing all plants around them and costing nearby allies a Healing Surge. This power got expanded with the Master Defiler paragon path, which culminated in the ability to suck the life out of enemies to fuel the spells you promptly blew them up with.
Defiler is a shoe-in for a new Wizard class option when the 5th edition Dark Sun splatbook comes out at last.
Defilers are also one of the seven Houses appearing in Demon: The Fallen: the former angels of water and desire.