Halo 4 features the following Specializations:
Wetwork Specialization: Spartan optimization for stealth operations which focus on the elimination of an enemy target with the goal of leaving no tactical footprint behind.
Stealth Armor Mod: The Stealth armor allows users to move quickly and silently in combat, executing enemy assassinations with lightning fast dexterity.
The Stealth armor mod – which has very sharp shapes and angles, reminiscent of a knife or blade – does a number of things to help a player that likes to get up close and personal. It adds sound dampening when sprinting, animations are performed faster (to minimize the time you’re vulnerable), and it has a minor effect on Promethean Vision. Typically, when Promethean Vision is activated, people appear red. When you use Stealth, though, only your outline appears red. Many times when someone is using Promethean Vision, they scan quickly so if there’s a lot going on, they may miss you. Or you can hope, anyway.
Wetwork gold visor, Wetwork blue/orange visor, Wetwork armor set, Wetwork armor set variant, DMR Weapon Skin
Pioneer Specialization: Spartan optimization for deployment into uncharted, hostile territory (such as uncolonized worlds or Forerunner constructs like Requiem) for the purpose of gathering/relaying information.
Fast Track Armor Mod: The Fast Track armor mod allows Spartans to gain more experiential data from each encounter, effectively ranking up quicker during the process.
The Fast Track armor mod features armor that has wiring which runs throughout the armor to control temperatures in extreme conditions. Gameplay-wise, it gives the player more post-game experience. In-game, if you get 10 points per kill, you don’t get more at that exact moment, but after the game it modifies the amount of experience your Spartan earns to increase the speed at which you rank up. It’s not for everybody because it takes up a primary spot (that could be used for something like carrying an extra grenade or sprinting longer). And, in case you were wondering, you can’t change to it at the end of a game and get more experience for the entire match. Yes, we’re on to you…
Pioneer gold visor, Pioneer silver/blue visor, Pioneer armor set, Pioneer armor set variant, Plasma Pistol Weapon Skin
Engineer Specialization: Spartan optimization for the subversion, repair and reconstitution of a wide range of technology, including Covenant and Forerunner complex networks.
Drop Recon Armor Mod: Armor mod allows users to predict the location and time of an Ordnance Drop through an external suborbital monitoring system.
The Drop Recon armor mod – the helmet of which has four socket connections for add-ons, depending on the task – lets you know that Infinity Ordnance is coming and what the Infinity Ordnance is. You see the waypoint and type of weapon that is coming down prior to the weapon entering the game (the specific time is still being fine-tuned). Organized teams will find this armor mod useful because, with communication, there is the likelihood you can beat everybody to the weapon spawns your team finds most desirable.
Engineer gold visor, Engineer pink/purple/blue visor, Engineer armor set, Engineer armor set variant, Suppressor Weapon Skin
Tracker Specialization: Spartan optimization for long-range target tracking (trans-continent and off-world), particularly in scenarios where conventional tracking has failed or such a substantial time has passed that the trail has gone cold.
Requisition Armor Mod: The Requisition armor mod allows users the ability to recall their own ordnance requests in order to acquire more helpful weapons in the field.
The Requisition armor mod – the helmet of which has a scanning device on the front of the visor – allows you to choose a new set of personal ordnance when personal ordnance is granted. When the menu for a personal ordnance appears on your screen, hitting left, down, or right on the D-pad selects the relevant option. When you have Requisition and hit “up”, you receive a new random selection of choices. This armor mod doesn’t have knowledge of what ordnance had previously, so while you’re not guaranteed better choices, you’re more likely to get the weapon you’re good with or your favorite power-up, if you didn’t get it the first time around.
Tracker gold visor, Tracker purple visor, Tracker armor set, Tracker armor set variant, Boltshot Weapon Skin
Rogue Specialization: Spartan optimization for single-operative missions which require a lone Spartan to be deployed on their own for incredibly long durations of time, even years if required.
Stability Armor Mod: The Stability armor mod allows users to increase their aiming stability when being fired upon.
The Stability armor mod – which features several sharp fin elements and sharp angles – makes you flinch less when you’re zoomed in and getting hit. It will be valuable to players that prefer using precision weapons and often find themselves engaged in long-range battles. If two similarly skilled players, both with DMRs and using scopes go head-to-head, the person using Stability has a small advantage. Skill and steady hands will still win the day but Stability allows you to keep your aim on target when facing multiple bullet strikes. Similarly, the player with DMR and Stability will have a larger advantage over a player with AR at long range. But (and yes, there’s always a “but”) the player they’re fighting may have made a choice for a different mod in that slot, which may come into play with an additional grenade or something else. Victory is never guaranteed…
Rogue gold visor, Rogue red/orange/silver visor, Rogue armor set, Rogue armor set variant, Carbine Weapon Skin
Stalker Specialization: Spartan optimization for target shadowing missions which require tactical invisibility despite operating at an extremely close range to the target itself.
Nemesis Armor Mod: The Nemesis armor mod allows users to target and track down previous attacking enemies, highlighting them on the armor’s passive sensors.
Nemesis armor – which features lines that are both strong and stealthy – gives you an icon on your HUD of the last person that killed you. While some people utilize it to get revenge, others use it to avoid that person (for obvious reasons). It’s also useful when playing defense for seeing where an offensive player is going. On maps with limited visibility, Nemesis can provide a short window of intelligence in the movement of enemy players or teams, allowing a respawning team to react and steal a match. In play testing, we’ve seen players trusting the extra information implicitly and falling for feints or being target fixated with the extra information and being lured into unfavorable situations. As with everything in Halo, this upgrade allows you to tailor your play to your style but remember that the enemy team is aware of the ability and will be countering and often using it or another option to tip the scales back in their favor.
Stalker gold visor, Stalker yellow/green visor, Stalker armor set, Stalker armor set variant, Battle Rifle Weapon Skin
Pathfinder Specialization: Spartan optimization for deep, unconventional deployment within unknown enemy territory and with little to no assistance from command.
Gunner Armor Mod: The Gunner armor mod decreases the time of weapon overheat when occupying a vehicle weapon position and increases Spartan speed while carrying a detached turret.
The Gunner armor mod – which was designed to explore alien worlds – has two major functions: One, when you’re on a mounted anti-infantry gun (Warthog and the secondaries of Wraith, Scorpion, etc.), the guns overheat less quickly, allowing you to fire longer at the maximum rate of fire. And two, when you pull the gun off an emplaced mount, you move faster, allowing you to use those guns more effectively offensively instead of just defensively. You still won’t be able to use Armor Abilities or Sprint, but you can move faster, bringing some heavy firepower to any offensive attack.
Pathfinder gold visor, Pathfinder orange/green visor, Pathfinder armor set, Pathfinder armor set variant, Assault Rifle Weapon Skin
Operator Specialization: Spartan optimization for the operation and control of a wide-range of vehicles; space, air, ground, and sea.
Wheelman Armor Mod: The Wheelman armor mod gives Spartans the skill to coax every bit of stamina and durability out of vehicles they are piloting.
Wheelman armor – which features cylinder packs that could be preplaced with more oxygen or cooling material depending on the mission – makes you suffer the negative effects of an overcharged Plasma Pistol burst for less than the normal time. Vehicles you drive are also more durable over a longer period of time. You can still get hijacked, but the window for that is smaller.
Operator gold visor, Operator orange/purple visor, Operator armor set, Operator armor set variant, Magnum Weapon Skin
Source: The Halo Bulletin: 8.15.12