Balance in VI2
Imperial Navy
The Imperial Navy by the turn of the 42nd Millennium is a battered force, besieged on all sides, and cut off from many of it's own fleets; battlefleets have been forced to abandon millennia-old dogmas to remain an effective fighting force. Represented by the fact that you, as an admiral of the Imperial navy, have access to the entire arsenal of the Imperial Navies ships at your disposal. From Relentless Class Training Cruisers and Duke Class Picket Cruisers taken from their auxiliary servitude to serve in front-line combat roles; to venerable Reprisal Class Battleships not seen since the Horus Heresy and new-generation capital ships in the form of the Nemesis Class Fleet Carrier and the Invincible Class Fast Battleship. Even old and obsolete classes, like the Corinus and the Cardinal (better known by their heretic names, Repulsive and Acheron) are in use with the Imperial Navy. This grants the Imperial Navy unprecedented versatility, and a tool for defeating any enemy of the Emperor.
Despite it's losses, the Imperial Navy remains as the largest conventional fleet in the galaxy, and can reliably outnumber many of it's enemies. For this reason, point costs across the board have gone down. In particular, the Imperial Navy can call upon their vast fleets of very cheap (but competent) Line Cruisers to overwhelm their enemies, and form some of the most formidable capital-ship gun-lines in the entire galaxy.
The Imperial Navy also enjoys better turret and troop ratings than they did before in vanilla. This is to represent the hardiness of IN vessels, the fact that despite being ships of 'mere men', they require a truly savage kicking before they finally cease in their duties to the Imperium. They will bitterly resist any form of assault, be it from capital-grade fleet weaponry and strike craft assaults, or the most savage boarding assaults the grim dark galaxy can throw at them.
Adeptus Mechanicus
The AdMech answer the call for aid with a far more formidable fleet then what has been seen prior. They have received weapon upgrades, thrusting forth into battle with many new versions of existing ships and new never-before seen ship classes based on designs from times long-forgotten. These new classes include a wide variety of arcane Line Cruisers, such as the Myrmidon Class and the Secutor Class, and many 'new' variants of the venerable Ark Mechanicus revealed to the galaxy at large following the Fall of Cadia. They also make use of modified SM warships, as they control the planets that create them. It is a fleet which, unlike the Imperial Navy, does not rely on numbers or endurance to grind it's opponents into submission; but rather a well-oiled machine of mass destruction, intent on obliterating it's foes with extremely powerful weaponry from a safe distance.
The Adeptus Mechanicus, to ensure these stand-off tactics are a success, have more powerful fighters and bombers at their disposal than those variants in common use with the IN. They also have much more powerful ordinances. Their Nova Cannons and Torpedoes dealing more damage than the more standard variants of the IN, and many of their ships featuring both torpedo launchers and nova cannons, even their new Grand Cruisers are fitted with Nova Cannons. Any attempt to counter these tactics with carriers are also much more likely to be met with failure, as the defensive turrets of the AdMech are much more powerful than those of the IN.
Despite their ships being much more expensive, and thus wielding smaller fleets overall, it would be foolish to assume this makes the AdMech a fragile faction incapable of brawling. They have powerful shields across the board, and very tanky Battleships. Provided the Adeptus Mechanicus is able to pick and choose its fights, there are only a few factions in the galaxy that can reliably best the AM even at close range, such is their fearsome firepower with all forms of weaponry.
Space Marines
The Space Marines are the Imperium's elite, and they have access to the most powerful ships and crews of all the Imperium's fleets. Their ships are extremely tough; with thick armour, heavily buffed health pools and the most powerful shields the Imperium can afford to give them. These ships are generally fast and responsive, pack impressive firepower and have very dangerous boarding potential.
The one exception are the Battle Barges. These ships are slower than in vanilla, as they are now true mobile fortresses with fearsome firepower and outstanding turret and troop based defences to go alongside their thick shielding and strong hull. They are extremely difficult to kill and can best most battleships one-for-one, even the Necron Cairn should think twice before closing with one.
The only real weakness of the Space Marines are their numbers. Represented by very costly ships, they have by far the most expensive fleet of all the Imperial factions and are thus the smallest fleet, but they are versatile and very powerful. Having the highest endurance and mobility of all the Imperial factions as standard.
Chaos
The Chaos warfleet is very much a force in ascension. Going from strength-to-strength, as more heretics and degenerates join their ranks, the Chaos warfleet is greatly swelled in size and variety. These include many new cruisers, heavy cruisers, grand cruisers, battleships and titans; filling a wide variety of roles. Fleet flagships like the Warmaster Class Battleship and Corrupter Class Fleet Carrier making an appearance alongside heavy raiders like the Blasphemer Class Fast Battleship. Their new formations also include Traitor Legion warships in the form of older now-heretic patterns of the venerable Strike Cruiser and Battlebarge; but they are no less dangerous than their loyalist kin. This variety affording them similar versatility to the Imperial Navy, making them very much the twisted reflection of the Emperor's Shield; instead embodying the dagger aimed at the Imperium's heart.
The ships of Chaos are generally less durable than their loyalist cousins. They have lower health, and less effective troops and turrets for defence, for they have far less reliable methods of recruitment, maintenance and training than their hated Imperial rival's goliath military industrial complex. This also accounting for why their ships are generally more expensive, as the Chaos warfleets can not call upon the same vast reserves of ships and manpower that the Imperium can. But what the Chaos fleet does have is speed, range, plentiful heavy carriers, powerful boarding options and overwhelming firepower. The Chaos fleet being highly adept and skilled in the art of controlling it's engagements and utterly defiling it's enemies with well-timed and overwhelming aggression. Chaos prefer not to engage in the same kind of attritional gun-battle the Imperial Navy thrives on, choosing a combination of long range kiting and decisive brawling-melee battles.
Necrons
The necron fleet is the most dangerous fleet in the galaxy. They are the toughest, one of the fastest and possess by far the most powerful individual warships of any other fleet. They have a greater variety of vessels than in vanilla, to fill more tactical roles and to allow for greater fleet diversity; and have had a whole range of buffs granted to them in all departments as well as extremely hefty cost increases.
They are the smallest fleet, to compensate for their power and flexibility, and will be quickly overwhelmed by a competent enemy if they do not constantly seek to control the engagement and focus down the most dangerous threats. But to a Necron Overlord, this should be a trivial task, and the greater number of pathetic vessels the lesser races endeavour to throw at you are little more than fodder before your majestic dynastic war-fleet.
Orks
The Orks are brutally simple and simply brutal. They have a lot of ships, with a lot of powerful guns, and a lot of health. Point-for-point you will struggle to find a race that gives you more for what you pay. Just be wary, as although they have had a greatly expanded fleet in terms of size, they are still an inflexible and short-range fleet that can easily be kited by most factions.
Ork Roks have been reworked, they are now much more powerful, but also quite slow and very expensive by Ork standards. They are like anchors for the Ork formation. Acting as the fulcrum of an assault and a solid rok against enemy aggression. The Orks also received a few new battleships, including a new carrier battleship and a lance battleship, as the Orks are as-ever as cunning as they are brutal.
They are in some ways similar to the IN in their preferences and faction-flavour, but Orks have the decisive advantage in close range with their strong boarding and even-higher endurance and firepower for their costs than the IN.
Eldar
All three Eldar factions have changed to some extent, some more than others, to better represent their three distinct fleet doctrines. Although all Eldar have generally very fast and very expensive ships with powerful offensive combat capabilities.
Corsair Eldar have the strongest lances, and are in the middle in terms of endurance and speed. They are the most versatile, able to fill a variety of raid-oriented combat roles, as well as having the most powerful escorts and carrier vessel of all Eldar.
Craftworld Eldar have very limited range, their macros limited to 4.5K range with no way to buff it (with the exception of their flagship), but they are the most durable and have the highest Macro DPS of all Eldar factions. They are brawlers, through and through, preferring a sweeping melee battle over hit-and-run tactics favoured by their pirate-enthusiast cousins of the other two Eldar factions. They are also the slowest Eldar faction (although they are by no means 'slow').
The Dark Eldar are blisteringly fast, the fastest faction in the game by far, but they are also by far the most fragile faction even among Eldar. To compensate, they have extremely long range macro weapons (reaching out to 18K in some cases), and have some of the highest DPS-to-point ratios of any faction in the game. Combined with their ability to stealth, and the strongest strike craft in the game (even their bombers can easily outrun almost any other faction's fighter screens and deliver punishing ordnance); they are a brutally efficient raiding faction. But they must not, under any circumstances, be caught in a pitched battle with any other fleet. They will lose.
Tau
The Tau function in much the same way that they always have, they deliver punishing firepower from great distance and have flexible vessels able to direct all of their firepower directly forwards. They have received damage buffs, and price adjustments, to ensure this theme remains constant despite other changes made.
Otherwise of note, the Kroot Warsphere has been significantly buffed, Ion Cannons now deal much greater one-shot damage than before (and a higher crit rate) and the Tau Merchant's prices almost universally have been reduced.
Tyranids
The Tyranids have been worked into a true swarm faction. They have the cheapest cruisers and escorts by far, and some of the cheapest BCs and BBs in the game are also theirs. This means, by sheer size, the Tyranid fleet is by-far the largest. Able to bring the most ships to bare for the point limit out of all the factions in the game, allowing them to completely envelop and overwhelm their enemies in close quarters.
In addition, Tyranid weapons have received buffs and their strike craft now hit harder on the offence. Although, as before, and much like the Orks; they are an inflexible fleet, and they definitely lean much more heavily on their ridiculously deadly boarding and ramming abilities rather than sheer endurance and firepower like the Orks.
Dominatus Addon by Imperator:
Most of what Caliger outlined above is true for the Addon as well. However, there are a few key differences:
Space marines have replaced Tyranids as the champions in boarding, delivering devastating critical damage with their precision sabotage. Tyranids are now number 2, with AM, Orks and Dark eldar fighting for third place.
The Adeptus Mechanicus ships are more expensive, but have been reinforced by Skitarii and Mechanicus fighting units that the new codexes have made, thus delivering a terrifying, radiation sickness inducing boarding action, third due only to the Tyranid's vast numbers.
Fleet sizes are also roughly 50% larger, and Eldar are closer to vanilla. This mode is less balanced, more intended for lore-friendly fun.
