Warmachine is a tabletop wargame produced by Privateer Press set in the Iron Kingdoms setting. It is the sister game to Hordes, with which it is fully compatible. Most discussion and tournaments include both Warmachine and Hordes, leading to the portmanteau "Warmahordes" (unsurprisingly more widely-used than the alternative portmanteau "Hormachine").
The Iron Kingdoms setting is the result of a fairly generic high fantasy continent developing steam-powered technology to repel evil liches from
SPAAAAAAAACE across the ocean. Since then, they've engaged in World War I-style trench warfare between the various nations on the continent. However, this is complicated by the use of multi-ton, steam-powered robots called Warjacks (usually shortened to just 'jacks), which are magically bonded to battle wizards known as Warcasters. There are also power-armored, Russian-style Man-o-Wars; bearded elves with bows; machine-enhanced zombies; and squads of paladins with swords that set people on fire. The Iron Kingdoms setting is also famous for actually moving forward; for instance, Llael was an independent nation in the first book, but the northern half was soon occupied by Khador and the people turned to a guerrilla resistance war. Then the southern half of the country got invaded by the Protectorate of Menoth, and became an even worse place to live. Basically, stay the heck away from Llael.
In terms of scale Warmachine is considered a skirmish-level wargame, which is generally much smaller than Warhammer 40,000 or Warhammer Fantasy Battle. Indeed, the smallest games can be run with no more than four or five models. However, the game can expand to a scale similar to the 40k, with armies numbering 50 or more models per side. However, even at this scale, it tends to play faster than the two Warhammer games thanks to a broken-down system of resolving turns (each unit/model 'activates' and resolves its turn's actions individually, and once a player has activated all their units the player's turn is over) being staggered; after activating a unit, the other players gets to activate a unit and so on.
Privateer Press, the publishers of Warmachine follows a different (and, according to some, better) update schedule than the Games Workshop games with which they compete. Basically, each faction has a "Forces of" book with two short stories, background fluff on the faction, theme force rules and the unit profiles for a number of models. Unlike Games Workshop's books, these are permanent and are not regularly updated. Instead, Privateer Press puts out expansion books that include new fluff and units for every faction, at the same time continuing the metastory of the Iron Kingdoms (rather than retconning the shit out of past books). On one hand, this means the plot actually moves forward and doesn't stay the same for over 20 years, but on the other hand, it the ongoing story can make it harder to keep with everything that keeps going on.
Warmahordes is generally a well-balanced game: All of the factions have their niches and are all able to pull off a win if the list is well put together. Furthermore, almost every unit in the game has a a trick and a role in which it can fit well at least some army lists, even if it's not the best model for the job, avoiding disasters like the Pyrovore or Mandrakes. That being said, there is a downside: whereas 40k and Fantasy are strongly focused on your dudes, with a ton of options for every unit, Warmachine is relatively limited. Units must be taken as-is, and your army must be led by a named character Warcaster. Some people do not find this a problem, but those that like to "forge a narrative," as Games Workshop promotes, will find it disappointing.
 Unit types
 Warcasters and Focus
Games of Warmachine tend to revolve around a Warcaster, a powerful battle-wizard that can forge a mental link to warjacks. In addition to warjack control, your average warcaster is far more powerful than any other warrior on the field, with superior statistics and weapons and a magically-bolstered health bar, and can easily match a whole squadron of warriors if the warcaster dictates the terms of the fight. How you build your army in this game generally revolves around your choice of warcaster: each warcaster has a spell list that focuses on a certain strategy or supporting certain types of models, so you should build your army in accordance with that. It's possible to completely change the dynamic of an army simply by changing which warcaster runs it.
At the start of each turn, a warcaster automatically generates Focus points equal to their FOC stat. This stat is between 5 and 10; the average is about 6 for heavy melee fighters and 7 for spell-slinging squishies. They then get to either hog the focus for themselves or allocated it to their warjacks, with warjacks being able to receive up to three focus at a time from allocation. Most warjacks can't hold on to focus between turns, so allocating focus is all about calculating the minimum number of points that the warcaster and their warjacks will need to wreak the maximum amount of destruction. When on the warcaster, focus can be used to generate additional attacks, add an additional D6 to attack or damage rolls, or cast spells. Any unspent focus on a gets added to their ARM value at the end of the player's turn. Saving a little focus at the end of the turn can help a warcaster (especially a squishy one) shrug off weak ranged attacks that would otherwise chip away at their health. If you're not using your Focus, you're doing the equivalent of dropping your soap while in a prison shower.
Spells have a wide variety of effects. There are straight-out offensive spells to use if you are boring and have nothing better to do with your focus (protip; you will have something better to do with your focus), but the majority of spells provide buffs and debuffs which, if applied correctly, will turn your army into an engine of destruction. Some spells have the "upkeep" property, which means that you can sustain their effects for more than one turn if you pay a single focus point at the beginning of each turn. A warcaster can only have one copy of each of their upkeep spells out at a time, and a single unit can only have one friendly upkeep on it at a time. Some players like to use seriously complicated plans involving swapping upkeeps between different units; it is fun to make these players cry with the Purification spell, which strips all upkeeps within a very large radius.
As well as their spells, a warcaster can use a feat once per game. A Feat is a unique ability that can have a huge effect on the battle; some are fairly hard to pull off or have only mediocre effects, but the majority allow for game-swinging plays when played correctly. Since they're one-use, make sure you know what you're doing when using them.
Under the default rules, if all of your warcasters die (and you'll probably only have one in most games), you lose regardless of the current situation, so many strategies revolve around trying to kill your opponent's warcaster. If a warcaster dies, all of their warjacks shut down and become very large paperweights until someone gives them a kick up the backside (said kick requiring an action and thus being a very expensive kick), so killing warcasters is very valuable in multi-warcaster games too.
Warjacks are basically 7-ton steampunk Hunter-Killer Terminator golems; tactically equivalent to how we use tanks in Earth warfare, but with 100% more awesome. Warjacks pack crazy powerful weapons, heavy armour, and huge amounts of health, making them the most powerful individual models in an army that isn't a Warcaster. The downsides are that they're usually slower, easier to hit, and less accurate than infantry, and they cost a bundle for a single model (so they're pretty easy to flank).
Warjacks generally rely upon a warcaster to improve their offensive potential. A warjack can be allocated up to three focus per turn from their warcaster's focus pool, and some warjacks can be allocated or generate additional focus with special rules. They spend this focus to run, charge, make additional attacks, add extra d6's to their attack and damage rolls, or make power attacks like throws, slams, head- and arm-locks and tramples. Power attacks are automatically hilarious and should be done as often as possible. Alternatively, some units and solos have the "'Jack Marshal" ability, which allows them to control warjacks without magic (mostly through shouting and rude hand gestures). This is roughly akin to controlling a computer without a mouse, but can be viable as a way of pulling some focus load off your warcaster or sending a warjack down a flank outside of the warcaster's allocation range.
Unlike other models, which mark their damage on a straight-line health bar, warjacks have a 6-column damage grid. When they take damage, you roll to see which column the damage goes into and start marking down, rolling over into the next column if the one you're marking is full. These columns contain letters which represent the warjack's systems; if every letter for a system is marked, that system is "crippled", and the warjack suffers a significant drop in performance. For example, crippling the warjack's cortex means it can't be allocated focus points, and crippling a weapon system means that system rolls one less d6 for attack and damage. Warjacks may be tough enough to shrug off a single infantryman's attack, but are far from invincible; many infantry units can gang up in a Combined Attack to hit with enough power to make a warjack think twice, and some units are specially geared up to be able to take down warjacks in a single turn.
Colossals are like Warjacks with more FUCKHUEG, because Privateer Press wanted to charge $100 per model for something, and the only way to do that was to make it really big (and, unlike Forge World models, almost actually worth it). Roughly equivalent to Titans in 40K (but newer, both fluff- and crunch-wise), they can be fielded at any point level (even 15pt games, though good luck fitting more than just a 'caster and a Colossal on that list). Colossals are surprisingly well-balanced, since they have about the same defensive stats as a heavy warjack but loads more health and tons more dakka, as well as access to several Colossal-exclusive power attacks. Oh yeah, and they have TWO 6-column damage grids to play with, although they generally have less than double the health of a heavy warjack.
If you're up against a Colossal and your army is mostly anti-infantry, you're hosed.
Units are groups of models which fight together as, well, a unit. One of the models in a unit is designated the "unit leader", and the members of the unit are in coherency if they're within a certain number of inches of their leader. The infantry models in a unit usually only have one hit point each, meaning that damage rolls are often superfluous. If the leader dies, then a grunt from the unit gets a "field promotion", so you replace his model with the unit leader's model and panic because most of your unit isn't in coherency any more. Units are bought in bulk rather than individually: most cost from 4-6 points for a minimum-count base unit (there are some more expensive ones that can centerpieces for your army), with some units giving you an option buy extra numbers and special Attachments. Attachments come in two flavors; Unit and Weapon.
Unit Attachments (UAs for short) tend to be officers, standard bearers or other 'command' elements that buff your units and give them new tricks. An example is the Cygnaran Gun Mage Officer (AKA The Dude) who not only gives you an extra gun that is aimed better than vanilla Gun Mages, he gives the entire unit True Sight (ignores stealth and concealment), AND can also marshal a Jack along with giving it the Gun Mage-exclusive Rune Shot attack types.
Weapon Attachments (WAs) expands the offensive ability of a unit more directly; WAs are weapon specialists like the Winter Guard Rocketeer (the RPG guy) which are added on to the unit individually, and not only provide more bodies but better weapons too. If a WA bites it, though, there is the 'take up' rule which lets you remove a regular trooper as the casualty instead.
Finally, there are things called Solos, which are like units, but with only one model (hence, SOLO). They are typically independent characters who have either lots of special abilities to support the rest of your army or debuff the enemy, or absolutely absurd killing power and stat lines. Almost all of them have at least five hitpoints, meaning that while they can certainly survive the sorts of attacks that would kill the average trooper, but anything high-power enough to dent a warjack is probably going to kill them outright (if it hits anyway). Solos tend towards being hard to hit rather than being able to tank big hits.
 Battle Engines
Battle Engines are recent additions to the game (recent years, but before the Colossals). They are big, durable, vehicle-sized models on the same 120mm base as colossals, built with a certain task in mind, like support or shooting. They cost about as much as a heavy 'jack, and are generally much more specialized and slightly less durable, but also don't need to draw from a warcaster's focus to do their thing.
Characters are not a unit type of themselves; rather, they are uniquely named units, solos or warjacks that are exceptional in one way or another. All warcasters are characters, but other characters include talented mercenaries (Rutger Shaw, Eyriss), charismatic leaders and their followers (Alexia Ciannor and the Risen, Greygore Boomhowler and Co.) or warjacks that haves been around long enough to develop a distinct personality or been sufficiently upgraded to the point where it's no longer a normal warjack (Ol' Rowdy, Beast 09). Characters are unique and you can only take one of a single character in any list, no matter how big the army size; they are typically more expensive than their non-character counterparts, but also have better stat lines, abilities, weapons and skills.
 Epic characters
As the story of Warmachine progresses, so do some of the characters. Epic characters are characters who have been through traumatic events (like Deneghra2, who died and got raised as a wraith), gotten new shiny gear (like Stryker2, who got some experimental lightning-powered armor a big new sword) or found new resolve (like Eiryss3, who stopped being a mercenary and hooked up with the Retribution of Scyrah full-time). They are generally similar in playstyle to their original counterparts, but still different enough to be new and interesting. When building an army list, you can't have the regular and epic versions of the same character in the same list.
Regular and epic versions of characters used to be referred to with the shorthand "pName" (for "prime") and "eName" for ("epic"). However, recently, some characters have gotten up to their third incarnation. The Privateer Press forumgoers played around with terminology like "lName" (for "legendary") or "eeName" (for... "double epic"?) when referring to the third-incarnation characters, but Privateer Press has stated that it officially prefers the terminology Name1/Name2/Name3, which honestly is much easier.
Epic characters are, in theory, at the same power level as their prime counterparts (or at a power level appropriate for their new points value). However, there are a few isolated cases where epic warcasters, particularly older ones, are on the overpowered side, thanks to some remnants from the MkI edition of the rules. You see, in MkI, warcasters had a points value, and were limited in number by the total points value of the game (1 warcaster for every 500 points of models, I think, but I don't remember exactly). Epic warcasters had a higher limit (1 warcaster for every 750 points?) and usually a higher points cost to match. This meant that epic warcasters could be more powerful than their prime counterparts. In MkII, most of these epic casters were knocked back in power level to meet the demands of the new points system, but a few of them retained some MkI abilities which sat on the overpowered side of the spectrum. Asphyxious2 and Haley2 are definitely among the most overpowered models in the game, although you'll see complaints and debates about various other older epic warcasters as well (including but not limited to Caine2, Stryker2, and Sorscha2, as well as Lylyth2 from Hordes). The good news is that most of these warcasters are overpowered because of their feats, which fortunately only happen once. If you can weather the pounding that their feats will give you, you've got a good chance of clearing the game.
 List building
In the grand old wargaming tradition, every model has a points value and opposing armies have to be the same size. However, the points values of Warmachine are very small compared to GW properties. 15pts is a small-scale learning game with one warcaster, their battlegroup, and a few infantry or solos. 35-50pts is brick-and-mortar-store tournament scale (roughly equivalent to 1500-2000pts of 40K). 75pts is for all-day convention tournaments. Anything bigger than 100pts borders on Apocalypse scale; Privateer Press has released "Unbound" rules to streamline games at 150+ points, but they're still a bit on the clunky side.
Army sizes are given as "X warcasters, Y points". As a general rule, games will only have 1 warcaster up to about 100 points, when you start adding an extra warcaster for every 50 (2 warcasters at 100pts, 3 warcasters at 150 etc.). This is because Privateer Press wanted to guarantee waracasters and warjacks in any army. Warcasters don't have a points cost and are included for free. Warcasters also get something called "warjack points". These are extra points which can only be spent on warjacks under the warcaster's command, so a 'caster with +6 warjack points can take a "free" 6-point warjack or knock 6 points off the cost of one of his heavies.
The majority of tournaments allow you to write two different army lists and choose between them at the start of the game. This allows you to build one list which can cover for the shortcomings of the other. 1d4chan's official recommendation is to have one Searforge Commission Mercenaries list and one Talion Charter Mercenaries list, allowing you to field both dwarves AND pirates at the same tournament.
During the game, Warmachine uses d6 as its core mechanic, usually as 2d6 or 3d6 rolls, which produce a rough approximation of a bell curve. Common effects allow you to add an additional die to a roll, or allow you to roll an extra die and drop the highest/lowest, and conversely some effects also force you to roll one less die. From there, it's a matter of adding the dice results onto relevant stats and seeing if it is equal to or greater than an opponent's stat. A regular attack consists of two rolls; a roll to hit, which is 2d6 + melee/ranged accuracy, with the attack hitting if it is greater than or equal to the opponent's DEF stat; and a roll to damage, where the opponent takes 2d6 + the POW of the attack (+ the STR of the attack if it's melee) - their ARM stat in damage points. Every roll is made individually, and while it's possible to stack a couple of extra d6's onto a lot of rolls, you're very unlikely to need more than 5 of 6 of them (although the Forsaken from Hordes can roll a theoretically infinite number of damage dice if its opponent is very, very stupid).
The system never uses tables or charts, because everything is based on straight-out mathematical relationships, and it's further simplified by the fact that all units have their relevant info condensed into one or two stat cards including damage boxes, weapons and other special rules to allow for quick reference and faster gameplay. Better yet, relevant stat cards is shipped with every model, meaning you don't actually need a Forces of... book to play (though it's good for lore, tactical tips and to see what else is out there).
The game works to reward an aggressive play style; the first player to charge into combat usually gains a distinct advantage over the one that doesn't, and with game scenarios in tournaments almost always including a 'take and hold' objective of some sort, closing with the enemy is encouraged. This doesn't mean ranged- and magic-heavy armies are disadvantaged, though, because there are several special rules (Gunfighter, Point Blank, Assault) that allow ranged units to use their ranged attack stats and/or weapons for melee combat, and Warcaster spellcasting can even be done while 'engaged' in melee in addition to their usual complement of ranged/melee attacks. As always, though, ranged units tend to be much more squishy than their melee counterparts, and not all of them have rules that allow them to fight in melee.
Warmachine currently has six or seven factions, depending on who you ask. The sixth "full" faction, the Convergence of Cyriss, has only recently been released. The "seventh" faction, as it were, are Mercenaries. Normally, these are just guys you can take as part of another army, but Privateer Press has released a number of "sub-factions" that let you take Mercenaries as their own army. However, they insist that Mercenaries are not an "actual" faction and refuse to release any starter sets for the sub-factions.
Cries of "For the Motherland", red banners, gold triangle-stars, frigid bitches, and beardy berserkers personify Khador (as well as the Freeze/Cold attack type). They're a northern Imperial Russia/Soviet Union style nation bent on imperialist conquest. Khadoran armies tend to be smaller than other armies and usually slower, but their infantry and 'jacks tend to be much tougher and deal more damage, though good luck hitting something without boosts. If you think this is ironic since real life Russian tactics were more swarm based, it's quite possible (and even favorable) to make a mostly-infantry army composed of conscripts. Despite this being depicted as common place in fluff, big units of the conscripts cost more than units of elite troops.
On the whole Khador rely more on infantry than warjacks because their 'jacks and casters eat up a lot of focus, and they don't have any light warjacks, just more expensive (and more durable) heavy ones as well as (steam)powered armor Man-O-Wars. On the whole, they have the best armor in the game, at least at base values. Their small armies and simple play style, which allows them to also do decently well at ranged combat (not as a good as Cygnar, but no slouch), make them one of the best choices for beginners. Also, don't let their models speed stats fool you: the real slow factions in Warmahordes are Trollbloods and Skorne, Khador actually has a good selection of stuff that boosts speed.
Cygnar is the most advanced human nation; they tend to shoot things, hit things with lightning, or shoot things with lightning. They're made out to be a fairly nice place to live if not for the fact they have some bad blood with Khador (it's complicated, but TLDR Khador's been doing the Hitler thing to the local France/Poland-equivalent). They also have the Protectorate of Menoth wanting to overthrow their government (and religion), with the Cygnar/Menoth border literally running right through the Cygnar capital in a Berlin Wall arrangement (except that the Menites were smart enough to put their capital somewhere else). Just to make things all better, Cygnar's the closest to Cryx, who are aiming to exterminate them and everything else on the mainland.
Put simply, Cygnar would be a nice place to live in if the continent they were on wasn't a horrible place to live in. The other factions may not like each other much either (Khador has teamed up with them against Cryx), but Cygnar is basically in the middle of them all.
Their advanced understanding of magic and mechanics is reflected in that they have most of the best ranged weapons in the game, are best known for their Lightning attack type, and play less aggressively than most other factions (though they do still have some powerful melee models, which almost always have ranged attacks as well).
Compared to other factions, their warjacks also have better MAT and RAT so while they might sometimes be less durable they're better at actually making shit hit the fan (AKA their attacks, the other guy, respectively). Most of their units have the ability to shoot as well as fight in melee, giving them something of a combined arms feel. Their main weakness is that they tend to be fragile (then again, almost everthing is fragile compared to a Juggernaut heavy warjack) and have few in-faction 'tarpit' units that can soak damage and bog down enemy melee units. Like Khador, they're a good choice for beginners (in this case, those who prefer dakka over melee).
Also note that they have the widest range of mercenaries that will work with them, but more on that later.
Captain Maxwell Finn Their Stormwall Colossal is a fucking beast.
An island nation of pirates that was taken over by a Godzilla sized dragon named Toruk, the father of all dragons (dragons in the Iron Kingdoms are basically gods, and Toruk is the oldest and most powerful one who created the rest of them). Toruk wants to rule the world (or wreak random destruction, it's a little confusing), and aims to use the army he created in Cryx to aid in removing the other dragons, about the only thing that can kill him. Due to his concern about them ganging up on him, he spends his days sitting around doing nothing while claiming everything is going Just As Planned, whether or not that's the truth is unknown. Cryx is an interesting evil army, composed of pirates, undead pirates, ghost warriors, heavily armored liches, and demonic mutant witches. Their army is the fastest, cheapest, and largest on the table, and is for more advanced players, though this varies with how you build your army.
Cryx excels at being fucking tricky with some of the best warcasters in the game and plenty of cheap arc nodes (which can channel a 'caster's spells), debuffing the enemy, and utilizing "dirty" tactics, but is usually never quite as good in a stand-up fight. Their Corrosive status effect is also a nasty beast, as it auto-damages for one point. Modestly useful against 'jacks, nigh-inescapable murder against infantry.
Many of their models also have abilities that kick in when they kill enemy models, and as per the tradition of an army with undead units this includes adding models to their ranks. Cryx's jacks are the fastest and hardest to hit, and generally have fine melee accuracy and hitting power, but are also the least durable of all 'jacks and usually can't shoot for shit even if they have ranged weapons, which are pretty rare in the army as a whole (most ranged attacks in Cryx are likely to come from its Warcaster's spells). Their other main weakness is pretty standard for something that relies on debuffs; they don't have many buffs themselves, though here it varies much more widely on a caster-by-caster basis.
Has horny ladies with great racks, too. Really. This is a thing.
 Protectorate of Menoth
A bunch of religious fanatics that worship Menoth, the god of civilization and mankind, who is kind of an asshole. The church of Menoth began falling out with Cygnar about a thousand years ago since a more benign god named Morrow began gaining favor. While the two churches were able to coexist for hundreds of years, relations between them eventually turned sour, especially because the then-king of Cygnar favored Morrow. Eventually, the Menite church got sick of his shit, seceded from Cygnar (or were exiled, it was a little of both), wandered off into the desert, discovered petroleum, and endured even more oppression under Vinter Raelthorne IV before the Cygnarans also got sick of his shit and voted him out of office in the traditional feudal manner: with a military coup. The chaos resulting from this allowed the theocracy to form its own quasi-legal nation, the Protectorate of Menoth.
Technically speaking, the Protectorate is not allowed to have a military, which the Protectorate actually adhered to during its early years, but has lately began to ignore. They aren't really evil per se (they have legitimate Lawful Good paladins), but the leaders of the theocracy are, by and large, a pretty awful bunch. The Protectorate's main goal right now is to forcibly convert everyone back to the True Faith (well, at least the humans, anyway; Menoth couldn't care less about everybody else). Most recently, they invaded the eastern half of Llael, who quickly found that they preferred Khador's iron-fisted rule to the Protectorate's.
On the tabletop, the Protectorate is mostly about synergy, to an even greater extent than the other armies. Thanks to Menoth's sort-of ban on magic, their warjacks are shit; they have the slow speed and inaccuracy of Khadoran 'jacks and the fragility of Cygnaran 'jacks in one mediocre package. However, they can quickly become really, really good when aided by a Choir of Menoth, which make warjacks either bulletproof or murderiffic. They also love fire; although their ranged weaponry is about as accurate as a bottle rocket, it will set everything around it on fire when it lands.
As mentioned before, Menoth doesn't like magic much, nor does he like mechanika (seeing as how it's essentially magical technology). This means the Protectorate army is far more low-tech and has a ton of Gothic design to it. They favor Blessed weapons which all ignore defensive buffs over advanced technology. Their units include medieval knights and their warjacks have similar designs to many machines in the Imperium of Man. Their main drawback is that, without support, most of their stuff is pretty shit. Because of the necessity of careful synergy and combo-building in both making and playing their lists, Menite armies can be hard to learn. Magic players will feel right at home, though.
 Retribution of Scyrah
A bunch of jerkass elves who think that their gods are dying because human magic is draining their life force (whether they're right or not isn't stated), so they want to kill all human mages. Their units are designed very differently to any other army and have more of a sleek, curvy anime-esque look. They've got some interesting mechanics, like 'jacks with force fields, dedicated mage hunting units and a lot more magical weapons than most. Most of their army is either jack-of-all-trades units or units heavily specialized in a certain role. However, they're certainly one of the hardest and more expensive factions to play, limiting their player base. In terms of difficulty, if Cryx is Warmachine equivalent of the Eldar then Retribution is Dark Eldar (ironic when you look at the models and fluff), make a mistake and it's all over.
They're also fans of shaved heads and can even grow beards sometimes, making them the manliest elves ever, not that this is a high bar to
jump step over.
Beware of mittens.
 Convergence of Cyriss
New kids on the block, they are not a true robot faction (see Aurora), instead they're meatbags that transferred their souls into clockwork bodies using tubes. They worship a goddess of science and invention that exists as a planet in the night sky that drives you crazy if you look at it too long using a telescope, they've been around since the Witchfire trilogy so they're pretty deep in the lore, but have gone the opposite of the Sensei in 40k. Their warjacks inherit their controller's MAT and RAT, so a spellslinging warcaster is going to have average bodyguards while melee casters will have fairly scary warjacks. Each warcaster also gives a unique trait to all the warjacks in their battlegroup like an arc node, auto-repair or apparition. They field high-costed and slow heavies that usually serve multiple combat functions and extremely light and trash lights used to induct focus, prepare charges and clear lanes. Their infantry usually have two weapon forms, like a flail or whip and have the potential to out-tarpit Cryx with Enigma Foundries, independent vectors that rebuild dead clockwork vessels, including medium based infantry.
Once upon a time Mercenaries were meant only as additions to the real factions, so that two armies of the same faction wouldn't be composed of exactly the same troops. Since then, mercenary fans forced PP to make a number of mercenary "contracts" to allow them to play Merc-only armies. As of MKII Mercs possess some of the most awesome warcasters, including Magnus the Traitor/Warlord who has the most awesome backstory for a character in the game and some of the most annoying abilities ever. Mercs are awesome because they get paid to get shit done and literally have access to a character for every rule breaking exploit, except for Protectorate Choir of Menoth; no one gets anything that broken. That said Mercs currently have the best tournament meta advantage, as the 2 List format and contract system means that your opponent will have to face one of two armies who are radically different from each other and share no units (other than Eyriss and Gorman di Wulfe, but they're played by every single player who wants to win, and isn't Cryx) or common weaknesses.
There are four mercenary contracts in the game (there used to be five, but one of them got demoted thanks to new rules in MkII):
- Four Star Syndicate; Pick up every mercenary you own and put it on the table. Done. Allows you to play Magnus The Awesome or Epic Magnus The Super Awesome, without having to commit to tier lists (a tier 4 pMagnus list is pretty nifty though). Supposedly represents merc working for a huge mafia/trade consortium making this literally a PMC gone rogue.
- Highborn Covenant; they're French, see above and add some of your own models if you play Cygnar, since their list is composed of every model that will work for Cygnar plus gun mages. A bunch of rebels fighting to restore the nation of Llael. Said nation has been conquered by Khador, then half-counter-conquered by the Protectorate, so their prospects aren't bright. Considered the better contract in events, it has access to 2 Cygnar units that Mercs don't have a version of their own, a warcaster who is a combat monster against infantry and some mercs that are pretty good but not available to Four Star. Also has an army wide ability to redeploy solos after deployment is finished, but before the game, making it instantly better than Four Star.
- Searforge Commission; They're Dwarves and thus the only viable Mercenary contract not including a fellow named Magnus. Note, however, that the Dwarves in this universe are not Scottish, because the Trolls are already Scottish. It is generally agreed that the Dwarves in Warmachine have a New Zealand accent. Also, no beards (the elves stole them), except for the mad 'splosionmancer Durgan Madhammer, who has a short and scruffy neckbeard. Plays like no other faction due to Dwarfs being slow bricks while everything in this game is about aggression, that said 2 of its warcasters are pretty hard to kill and the third, Gorten Grundback is one of 2 warcasters in the game that are harder to kill than the army they lead, not mention he has a notorious buff which allows him to make one of his jacks have enough pow+strength to instagib light warjacks or one hand throw warjacks three times its weight back to their controller for the steampunk version of hitting someone with their own fists; never play assassination against Searforge, you will just solve their mobility issues.
- Talion Charter; A bunch of pirates. Lots of pirates. How many pirates can you imagine? There are more than that. Also, a peg-legged Napoleon dwarf. Also, a fuckhueg cannon that is easily the best damn artillery piece in the entire game if you manage to get anything in its line of sight. This group is all about synergy with their units, which on their own are the worst in the game. But start adding in their solos and unit attachments, suddenly you've got yourself a unit that can do some damage to anything, is annoyingly hard to kill, and can add models to it after killing them.
 Getting into Warmachine
Go to: http://battlecollege.wikispaces.com/ for more information and advice on how to start an army, as well as the official site: http://www.privateerpress.com/WARMACHINE/default.php.
Get a battlegroup to start with, they're that fucking cheap if you want to run even some of the 'jacks/caster that they come with.
It must be said that it takes far, far fewer dollars worth of Warmachine stuff to enjoy yourself than other games, though you can still spend as much or more as other games if you try. You'll be paying about the same price per model as you would for Games Workshop stuff, but you will be fielding a lot less models per army, and the game is actually fun (but not hugely balanced) at low points levels.
While that may be true in the past with the new prices on the games workshop website warmachine is now a lot cheaper. A single unit can run you $35 to $40 in warmachine but now for games workshop a tactical squad costs $60. So yes a lot cheaper now to play Warmachine especially since you do not need as many units. Also: a lot of the warjacks are sold as kits with the parts to make one of three jacks. with the use of magnets one can get a lot of jacks out of just a few kits
If you like a faction, don't let the "beginner/expert" bits above scare you. Some factions are generally trickier than others, but none of them don't have builds that even brand new players can find easy to use.
 See also