Soldier Skills & Equipment Guide (EU2012)

Introduction

When choosing abilities, there is a debate about how to choose them and a variety of opinions depending on your personal play style and chosen strategy. The fundamental question that must always be asked when making a promotion is one of specialization vs. variety. Does the ability give you a new skill, improve a skill, or assist the squad as a whole?

The Assault class is the most clear cut example of this: nearly all of its choices are between increasing the Offensive or the Defensive capabilities of the unit, either turning it into a frontal assault unit or into a flanking unit. You can mix both, or even give it an unique squad ability by choosing the Flush perk, which forces the enemy out of cover.

Again, all of these options depend on your style and strategy. Any abilities' effectiveness depends on the map and type of aliens faced. When you're only starting to play, it may be confusing to realize all of the advantages and shortcomings of each class. Take the Heavy, for example. Early on the Heavy can be a major source of damage for your team but, due to the much lower Aim numbers of the class, at higher ranks their ability to be a primary source of direct damage falls off sharply. An inversion would be the Sniper. Early on they are weak and difficult to manage but, once they have some experience under their belt and a good weapon, mid to late game they will carry your squad. The Squaddie abilities and weapon limitations for each class define their general roles

The important thing to remember is that the advice in this guide will fall into two categories. Some of the recommendations are just that, advice that you may choose to ignore if you so wish. There are in fact many successful ways to run a squad that involve wildly divergent tactics. However, there are some points that are not recommendations per se. Some options in the skill tree exist that are clearly false choices. It seems like they may be equivalent or one is slightly better than the other, but in practice one of the two options is so much vastly better than the other that it changes the situation from a choice to a basic calculation. This guide will outline the different points as well as give approximate weights to the talents where it is not 100% a clear cut choice.

Building an Assault

Next to the Sniper, the Assault is your big damage dealing class. The critical chance of an Alloy Cannon is lower than a Plasma Sniper Rifle but the damage is the same and the Assault has all sorts of tools to enhance their burst damage and given the correct circumstances they can easily do more damage than any other class. On top of this they are tough and mobile. Also, Assaults are the only class that has a choice between primary weapons and are perhaps the only class that doesn't have a clear cut build path. So without further ado...

Abilities

Corporal

Tactical Sense vs Aggression

Here starts the divergent path, Defense or Offense. One offers you a mounting defense bonus per enemy in sight, the other a mounting critical chance. Which one you choose should be dependent on how you are planning to play the Assault. If you choose the shotgun as your primary weapon you should be taking Defense perks. To put it mildly, shotguns do a ton of damage, you don't need to worry about doing more, you need to worry about surviving the stupidity a combination of run and gun and a short short rang weapon produce. As previously mentioned a 20 point defensive shift is stupendously potent. Furthermore defense bonuses become exponentially more effective as they stack. Low Cover, plus Ghost Armor, plus max Tactical Sense, plus a Dense Smoke Grenade means that the Assault has a 100 point defense shift, making him effectively invulnerable to any aimed attack. Even negating his cover via flanking means that given the Aim numbers of most enemies he is still invulnerable. Aggression should only be taken when you are using an Assault Rifle as a primary weapon, you need to make up the loss of damage that the weapon entails and you also will be in better cover most of the time with less people trying to murder you, thus needing less defending.

Sergeant

Lightning Reflexes vs. Close & Personal

In a way these skills duplicate each other, and provide one of the only easy choices in the tree. Put simply, Lightning Reflexes is better. Both of them are closing skills. One gives you immunity to an Overwatch shot, which is amazing, the other gives you a 30% critical chance to adjacent foes that degrades with distance. The idea being that with one you can survive to close, with the other you can make the kill once you are there. Needless to say, while combining Aggression and Close & Personal can give you a theoretical 80% critical on basic attacks, the fact is that you are already capable of dealing massive damage with very good critical chance on a basic shotgun (assuming good positioning). Not getting splattered by a Sectopod Plasma Overwatch is better. Also, since the bonus is contingent on distance you should think twice before getting it for an Assault Rifle build.

Lieutenant

Flush vs. Rapid Fire

In XCOM, murder is usually the best solution. The major question that needs be asked is 'will this help me kill?' Of these two skills we have a clear winner in the murder category. Taking a pair of shots, even at a 15% penalty will almost always offer not only a statistically greater chance of a hit but will offer you the chance to knock the damage ball out of the park. If you are running a Scoped up Assault Rifle build focusing on high crit, this is a no brain-er. If you want a reliable way to ding an enemy from range then this might be a good idea. Remember, the chance to hit is much higher on a Flush than a basic attack and you can expect a near 100% chance even at extended range. Home run numbers are great but Flush could be a reliable coup de grâce, especially if you are running a lot of Assaults in a squad. Which isn't a bad idea.

Keep in mind, Flush carries three flaws that make it nearly unusable in a mission:

1. It costs 3 ammo: so you can't use it every turn and will reload more often. Ammo Conservation (Foundry) alleviates this a bit.
2. While it drives the target out of its current cover, the enemy could go to different cover, or break sight range completely only to attack you next turn from an unexpected direction. Consider Grenades.
3. A guaranteed hit, it might be, but at reduced damage! Sure, it will take out an enemy on its last legs, but it is an easily ignored option for most threats (besides Drones and tier one).

Captain

Close Combat Specialist vs. Bring 'em On

This is a choice. If you are planning on a shotgun, Close Combat Specialist is not an ability to skip. It is a godsend against charging melee, the poor fool that wanders through a door you are next to, or any close range engagement. In contrast Bring 'em On has no range requirement but, if you aren't rocking the critical side of the tree, it is a very streak dependent talent. Under ideal circumstances, you can get a 14 damage critical from a Plasma Rifle, or two of them if you hit and crit on both of your rapid fire shots. Much more if you get Killer Instinct at Colonel rank. Needless to say, this is an amazing amount of damage, enough to waste near on anything. Critical rates on an Plasma Rifle with a Scope and the critical hit abilities will still hit a flat 80%, 50% if you choose Lightning Reflexes or if you aren't at point blank range. Higher if you flank a foe. As you can see this isn't a cut and dry situation. Both rifleman and shotgun are viable options.

Colonel

Resilience vs. Killer Instinct

On one hand you have immunity to critical hits, on the other hand you have a 50% damage bonus to your critical hits if you trigger your signature ability. If you have chosen to brawl then grab immunity to crits. It means you can't be take out in one round by any single foe and it takes luck out of the equation. Killer Instinct on the other hand only shines if you have been mining the tree for bonus crit chance. That being said, you can make some very aggressive plays with Killer Instinct. Run at full dash to a good position, open up with Rapid Fire and blow a Sectopod or Ethereal away in one fell blow, or two as the case may be.

Equipment

The answer is always Ghost Armor. Statistically it is just plain better. Now I wouldn't hold it against anyone who chooses Titan, but in the end Titan is just not as good for the up and coming Assault trooper. The Extra Conditioning from the Major promotion gives: 2 extra HP when wearing Ghost, Skeleton, and Psi Armor, and 4 when wearing Carapace, Archangel and Titan. The HP totals are as follows. Skeleton gives 5, Ghost , Carapace and Psi give 8, Archangel give 12 and Titan 14. Now the most bang for your buck early game is obviously Carapace, but once you have the money you should be investing in Ghost Armor. Why? Well for all the previously mentioned reasons plus one. In terms of survival Defense beats HP in smaller amounts, mobility is the bread and butter of an Assault trooper and here is the final reason. Ghost Mode gives a +100% chance to crit. This means that a Ghosted Assault can expect to reliably crit against a Hardened target if they are playing the shotgun game, and the rifleman can be sure of a crit. A massive Killer Instinct enhanced Rapid Fire crit that will level any foe you choose.

In terms of your free slot, the best choice is situational. I personally like Chitin Plating for my CQC troopers and Scopes for riflemen. The extra 4 HP offsets the losses that I sustain from not going Titan and gives you virtual immunity to Chryssalids and Berserkers. For riflemen, the Scope gives you +10 Aim and Crit Chance. Which is peachy. Use Mind Shields when appropriate.

Building a Heavy

The primary weapon of the Heavy is the LMG, and its Laser / Plasma upgrades. The weapon has a base damage of 5, which puts it in the high damage category along with the Sniper Rifle and Shotgun. It has worse critical chance than either, but it doesn't have the severe accuracy drop off that the Shotgun suffers from at any significant range and it doesn't suffer either the close range penalty or full turn cost of the Sniper Rifle. At first glance it is one of the best weapons in the game and in the early game it really is.

There is, as always, a hitch: in this case it is the Heavy himself. Starting Aim of all soldiers is 65 but, unlike his peers, the Heavy only gets 10 more points over the course of his life, with a Colonel capping out at 75. This means that at mid range and under optimal conditions the best Heavy will hit 75% of the time. If the target is in light cover that chance degrades to 55% and under High Cover there is only a 35% chance to deal damage. With a Scope you can improve a Heavy's aim to 85 but compared to the base Colonel accuracy numbers of an Assault, a Support or a Sniper, which are 89, 90 and 105 respectively you can see why the Heavy suffers.

Over a given hundred shots the percentile hit chance is a equal percentile modifier to Damage, meaning that assuming all enemies are in Low Cover, the base Heavy does on average a little more than half his listed Damage. This means that a Heavy at the top of the tech tree is doing the same as a Sniper at the bottom, less when you factor in the massive critical hit chances that the Sniper rifle enjoys, if they are both using weapons of the same tech level. This is discounting special abilities such as the Heavy's power to fire twice in a round, but suffice it to say that for every ability that the Heavy gets the Sniper of equivalent rank will gain an ever more insurmountable advantage. Now compared to a Support whose best weapon caps at 8 damage and who gets only 1 shot in a round the Heavy certainly does do more adjusted damage, but here in lies the problem. In real combat conditions you don't do an average damage based on your aim. You either hit and deal full damage, or miss and do none. If a Sniper did twice as much damage with half the accuracy its use as a unit would go from 'predictable' to 'coin toss' and its usefulness would drop from 'amazing' to 'marginal'.

Here is the thing. In a turn based game, the fundamental risk comes from uncertainty. If you are sure that an attack or ability will trigger then you can plan accordingly. Calculate exactly how much damage you can expect from all your units and use that to plan out a course of action. When abilities fail to trigger you are forced to make plans that accommodate this, namely, you need to devote more resources to a target than would under ideal conditions be needed, lest you whiff a final shot find yourself staring at a Sectopod with 5 hit points and it is now his turn. The binary nature of success and failure of individual actions maps to to the binary success and failure states of each turn. This is the beauty and the folly of a turn based game. The fact that a Heavy dealing with a standard foe in low cover with a 55% chance to hit cannot be relied on to make the shot means that you'll have to choose, both in game and during promotions on how to increase that accuracy or use the Heavy instead to prepare the Alien for the kill.

This is the paradox of the Heavy, they have amazingly high damage weapons but they require careful planning to make it an useful tool, and to be aware of the shortcomings that some choices can have, specially regarding perk selection.

Abilities

Corporal

Bullet Swarm vs. Holo-Targeting

• Bullet Swarm gives you massive tactical flexibility no matter how you choose to build the Heavy, Holo-Targeting a +10 Aim increase ONLY to other units firing at the same alien.
• Bullet Swarm allows for Fire and Move, Fire and Reload or Fire and Fire when high firepower is crucial. The issue, as mentioned above, is the lack of Aim of the Heavy - which makes this ability more useful in close range fights.
• The LMG has only 3 rounds, even if you take Suppression, you need Bullet Swarm to Suppress two rounds in a row.

A Colonel Heavy with a Scope shooting at an enemy in optimal range in Low Cover has as mentioned above a pathetic 65% chance to hit. If you go with Bullet Swarm and spend a full round trying to make the shot you have a 12.25% chance of missing totally a 42.25% chance of hitting twice and a 45.5% chance of tagging them at least once. Meaning that you will an 88.75% chance of hitting something. At lowest rank this would be a 79.75% chance to hit something, with a 30.25% of hitting twice.

Even though you might feel that there is a good choice here, there isn't. Using your Heavy to set up shots might seem like a good idea, but statistically it does not work. The problem is two fold, first, at the lowest levels when Holo-Targeting could most likely be useful, the power of at most 3 small 10 point bonuses does not produce more hits than an extra attack. Take the above situation. Enemy in Low Cover, Heavy takes the first shot, then one of each class chimes in.

4 shots with Heavy with Holo-Targeting taking the first shot. All Rookie Soldiers:

• 7.487% chance of 4 hits
• 27.422% chance of 0 hits

5 shots with Heavy using Bullet Swarm. All Rookie Soldiers:

• 1.845% chance of 5 hits
• 13.325% chance of 4 hits
• 11.603% chance of 0 hits

As you can see, the extra attack is better in every way. Not only are you going to have a higher chance of getting 4 hits, you will have a golden chance to hit with 5. Furthermore, given the fact that the Heavy has one of the better weapons, capable of killing any low level enemy in one hit the hits that a Heavy can make are worth more. Not to mention, this is a scenario skewed heavily in the favor of the Holo-Targeting Heavy. There are almost no early game circumstances where you will have a reason or the opportunity to make 4 attacks on 1 enemy.

I hope that one thing is very clear: NEVER take Holo-Targeting.

Sergeant

Suppression vs. Shredder Rocket

This defines your Heavy as either an explosives platform or a Suppression platform. I will make the argument that simply put, Supports are better at Suppression and Heavies should be blowing things up. Yes, Supports can't Suppress an area, yes, they can't use Mayhem to deal damage with Suppression but here is the rub, Supports have higher ammo / lower damage weapons with much greater accuracy. The Reaction Shot movement provokes will much more likely hit, the loss of damage is lower, there is less reloading needed and Supports have much more versatile ability to specialize. A Heavy with a Shredder Rocket has a 4 automatic damage weapon, that will hit exactly where put it (90% of the time, or somewhat close the rest of the time), and will amplify all damage against a target while removing its cover, in a wide area of effect. It is a limited use weapon but it will save you much more consistently than Suppression.

Lieutenant

HEAT Ammo vs. Rapid Reaction

A clean cut choice, as well. Many people who go the Suppression route think that this is perfect. Suppress an enemy, use Flush to force a move, let the Heavy get 2 free attacks. This is a failure state. First, reaction shots are made at a 15 point penalty and as we have previously stated Heavies have crap accuracy. Second, the only way you get a second shot is if the first hits, combine this with the aforementioned crap accuracy and you will rarely see this promotion trigger and even if it does trigger you still have to hit with it, at a similar penalty. On the other side of the equation HEAT ammo doubles damage against robotic opponents and affects all Heavy class abilities, including Rockets. Put simply, in XCOM, robots are the devil. The Cyberdisc and the Sectopod are two of the deadliest enemies you will face, anything that hastens them to the grave is awesome. A Cyberdisc is a deadly early game opponent who can deal 7 damage on a normal attack with a high critical chance, or fling a 5 damage Grenade half way across the map. It can and will one shot your mates, no one below major has a reliable chance of living, and only then if they are at full health. A rocket from a HEAT Heavy will deal 14 damage base, and can crit for more. Shredder Rockets will do 10 and allow your Sniper a good shot at a OHKO.  Not to mention, you will blow the drones that hover around the disc or the Sectopod sky high. Choose HEAT, a Heavy who can attack twice can one shot a Cyberdisc or wipe a Sectopod if both attacks hit.

Captain

Grenadier vs. Danger Zone

Less clear cut. In one hand you're holding two Grenades, in the other you have AoE Suppression and 2 tiles extra area on Rockets. Both are good abilities and the question of which you want depends highly. The benefits are more intangible and are linked to your final choice of what you want your Heavy to be doing. I am going to step back from (semi)objective analysis and offer an opinion. I choose Grenadier because by the time you reach this point, no one else on your team should be carrying Grenades. Your Sniper needs his Scope, your Assault needs armor of some type and even if she doesn't cause you are rocking Titan she should be doing a lot more damage with basic attacks than with a Grenade, Supports might be a good choice to heft a Grenade but they generally are better with Arc Throwers, Medikits, armor, or Scope. Heavies get natural damage ablation and multiple use actions. They have such bad accuracy that you aren't losing much by throwing an attack out the window, and the power that Grenades have to damage terrain and remove cover offers a much more powerful buff to accuracy than a Scope. The final argument for Grenadier is simply that Grenades are amazing breaching tools. You don't want to be using your rockets to breech but grenades can be a worthwhile trade. Danger Zone is lessened in value because you aren't, or shouldn't be, picking up Suppression, 2 extra tiles is nice on your rockets and is certainly worth more than a Grenade if it brings another enemy into range, but rockets are inherently less flexible than Grenades as with their full round cost. Don't feel obligated to get Grenadier, it isn't mandatory.

Colonel

Rocketeer vs. Mayhem

To many this is the a tough choice, but it isn't. Mayhem adds max of 3 damage to Suppression which we don't have and adds 2 damage to your rockets, of which you get only 2 (regular and shredder). Rocketeer on the other hand gives you a second rocket. Assuming that you don't even get the blaster launcher upgrade you are still falling behind by 3 damage, and lose the flexibility of a second rocket. Since we have already decided that the Heavy needs to be blowing things up to be reliable thus, anything that offers him more chances to be reliable is good. Thus, more rockets beat better rockets. With double Grenades you have 5 bombs that can reshape the battlefield in your favor. Alternatively, consider this: a heavy only has so many opportunities to fire rockets during a given mission. It's tough to set up a shot and securely have enough full turns to yourself to fire off all three you get with Shredder and Mayhem, plus throw two grenades. Thus, it may be better taking Danger Zone and Mayhem even if you don't have suppression, because widened range can really make a huge difference, and 2 extra damage becomes 4 against robots due to HEAT Ammo, which becomes even more effective with a Blaster Launcher. It certainly depends on your play style and whether you want to bother setting up for rocket fire.

Equipment

More than any other class, the Heavy shouldn't be worrying about their primary weapon. By all means upgrade the LMG if you can spare the resources, but there is a greater return on investment with other classes. Namely your Sniper and then your Assault need their weapons maxed ASAP, these are the classes that will be dealing your damage and the X-Rays drop Plasma Rifles and Light Plasma Rifles like confetti that your Supports or Assaults can use, thus obliterating the need to buy them. Moreover, the damage scaling is not as significant. With a five damage base a Heavy can reliably kill in one hit Sectoids, thin men and floaters on classic. To one shot the next tier of enemies a Heavy needs to upgrade to Plasma.

Armor is the really deceptive choice for a Heavy. Choosing a Heavy armor for your Heavy may seem right to you, but then you would be wrong. The role that we are looking to give to our Heavy is not that of a walking tank. That is you Assault. He needs to be mobile and capable of placing explosives precisely, while not being left behind. While Carapace Armor for everyone is always a wise choice compared to Body Armor, you should be considering Skeleton Suit and Ghost armor as your primary armors. Heavies don't get any inherent bonus from Heavy armor, unlike the Assault, instead they get a flat 2 point reduction in damage, meaning that they don't require a huge HP pool from Titan or Archangel.

Skeleton Suit / Ghost Armor offer your Heavy a couple amazing bonuses. First is that it gives you 3 extra move and the ability to grapple to the top of structures. Mobility powers are GREAT. Second they give you Defense bonuses, +10 health /+20 defense respectively. A clean miss is much better than more HP. Late game, in low cover, you can get a 40 point defensive shift if you are wearing Ghost Armor. All late game enemies do more than 10 damage a shot, and the 4 lost HP vs Titan or 2 hp vs Archangel or 1 in the case of Skeleton vs Carapace, is compensated by the clean misses. 20% off a 100% attack doing 10 damage is an average 2 HP gain. This makes Ghost even under the worst case scenario better than Archangel flat out and much closer to Titan than it seems. A Heavy in Ghost or Skeleton is more useful and almost as survivable. Psi Armor when appropriate.

Third, for Ghost Armor, the extra movement and the Ghost's unique ability to cloak allows the Heavy to safely get close or even flank a tough opponent in one turn, and then unleash a short range attack at optimum accuracy on the next. Similarly, this can be used to safely position the Heavy for a rocket launch.

Towards the latter part of the game, when it is available, the devastating Blaster Launcher replacement for the rocket launcher will increase the damage output of the Heavy's rockets and allow them to navigate around walls. The Heavy will no longer have to have direct line of sight to the target, but must be within rocket range.

For the Item slot, a Grenade or Alien Grenade is often a good choice for a Heavy. It provides an extra area-effect weapon (or two) that can be used to destroy cover in lieu of using a rocket.

The SCOPE or Chitin Plating are good general purpose items that help the Heavy shoot better or defend against close range attacks. The Heavy can also use other items depending on the Heavy's build or your needs.

Building a Sniper

The Sniper is the primary damage class that you will employ and suffers from a small problem of feast and famine. Snipers depending on the level will either be an unstoppable murder engine snuffing out at least one enemy every round, or they will spend most of the time running around useless trying to get a line of sight. Now building a sniper depends greatly on managing this problem, maximizing the good times and minimizing the bad. Snipers have the best basic aim progression of any class, reaching 105 at Colonel. With a Scope and high ground you can expect at have 98% or greater accuracy against an enemy in high cover and you can make the shot from across the map in a position of perfect safety. How can we assure this? Well lets go into the skills.

Abilities

Corporal

Snap Shot vs. Squadsight

DO NOT BE FOOLED! There is almost no circumstance under which you should ever be taking Snap Shot. To do so is a waste of epic proportions and you might as well be using another class instead of a Sniper. Now this being said, if you are trying some weird 6 Sniper team there is a possibility that this might be okay but lets examine. First, Snap Shot applies a 20 point penalty to any single action shot. Early game, this makes your shots untenable. A Corporal Sniper firing at mid range against an enemy in Low Cover has a 28% chance to hit. A Colonel has 65% chance, but good luck getting there. Second, a Sniper who wishes to have options in terms of close range engagement has other talents that can be used to do so. The gunslinger perk can give you a base damage of 6 with no aim penalties with a Plasma Pistol if you have a terrible need to move and shoot. Squadsight on the other side of the coin essentially defines a Sniper. Sniper rifles have a range cap of 100 which roughly translated is 4 times your vision range, or most of the map. Only thing is that you will never get this range unless you have squad sight. A Squadsight Sniper doesn't need to be right behind to your Assault to cover them. They can do that from the spawn.

Sergeant

Gunslinger vs. Damn Good Ground

This is a question of enhancing strength vs. minimizing weakness, only I put the order wrong. Gunslinger covers your weakness at close range and inability to scoot and shoot. Damn good ground makes you better at sitting on to of the world sniping the hell out of people. With a Scope and maximum elevation, damn good ground offers perfect chance to hit opponents in high cover. Without this perk you are slightly less than perfect but gunslinger makes it so that you can actually fight at close range and not fail. This is a toss up depending on your style. Just keep in mind that Archangel Armor does trigger Damn Good Ground, giving you slightly better than Low Cover worth of defense for free and an enhanced chance to hit.

Lieutenant

Disabling Shot vs. Battle Scanner

Of all the choices that you will make as a Sniper this matter the least. Disabling Shot is for the most part patently inferior to blowing someones head off. It is  harder to make, does less damage and is on a cool down. That being said, it can be very useful in capturing enemies and can once in a blue moon save your butt if you don't have the firepower to kill a Sectopod or a Cyberdisc. Battle Scanner on the other hand gives you intel, which is invaluable, but cannot be thrown far from the Sniper who likely will be in the back. Still, it can find enemies without triggering them thus allowing a sucker punch. Neither one of these perks will define your Sniper and you should feel free to choose them depending on your mood. One notable point however is if for some insane reason you are building a front line Snap Shot Sniper get battle scanner. You don't need squad sight to see through the scanner and it is the only way you can extend your vision. Also you will be close in and will have the proximity to throw it.

Captain

Executioner vs. Opportunist

This is another non choice. Executioner is a piddling 10% bonus that only triggers on low HP enemies. Snipers should be one shot-ing high HP enemies and pretty much the only people this will apply to are Sectopods, who already we have ways of dealing with. Opportunist on the other hand means that your Overwatch will do just as much damage at the same hit chance as your normal attacks and given the insane range on Sniper Overwatch allows you to protect soldiers all across the map.

Colonel

In the Zone vs. Double Tap

The Colonel level talent of a Sniper is pretty much godlike no matter what you choose. In the Zone is streaky, and maybe you're able to kill 8 aliens in a turn. But you should be aware of its conditions, to trigger In the Zone you must hit and kill an enemy out of cover or flanked. Practically speaking, your Sniper will never be flanking anyone, he will be well behind your entire line. So you'll have to destroy cover or target exposed aliens, like melee or flying units(flying units looks like to be in cover, but they're exposed units in terms of ITZ). Another way to trigger is Overwatching and killing a alien in move(which is exposed obviously), it'll give you bonus action next turn. As for the other choice, Double Tap is reliable. DT gives you second shot even if you unluckily miss first shot, every other round. And helps killing alien with large HP pool, like Sectopods.

Equipment

This is really simple. Give him a Scope, give him Archangel, get him the biggest gun you can get as fast as you can get it. For a Sniper, an upgraded weapon is your first combat priority. If he is above the tech curve the rest of your squad could be carrying pea shooters for all that it matters.

Building a Support

If you want to double up on a class, Supports should be your first choice. Sure they aren't as sexy as some of the others but they bring a lot more to the table than most suspect. First of all, Supports can shoot. They have great base Aim and full HP progression. Even without a Scope, a Support has a 90 aim. Beyond that they get to have 2 Item slots once they hit Major, allowing unparalleled customization. Furthermore they are fast, unless you have a stroke while promoting them and accidentally click the covering fire button they will be the quickest unit on the map. This along with their solid offensive and defensive abilities makes them the most reliable unit that you have. A team of all Supports would be a bit less than optimal, but is entirely possible to play. 

Abilities

Corporal

Sprinter vs. Covering Fire

Now I know, I said you had to be having a stroke to choose Covering Fire and might be a little harsh, but I stand by the statement. The issue is simply this: Covering fire will never help you. Why? Well, lets look at the ability. It grants you a Reaction Shot any time a unit under your Overwatch or Suppression fire. Sounds good right? No, its not. You just took a shot against a unit in Cover, that you could have fired on your turn, at a -15% penalty. It is nice if you are Suppressing an enemy, and it is also decent if you have the Sentinel ability, but the truth is that as Genghis Khan proved: mobility is victory. The ability to choose your ground is vital.

Sergeant

Field Medic vs. Smoke and Mirrors

I'm not gonna lie here. Smoke is awesome. Once upgraded it has all sorts if nifty perks and even in its base form a free 20 point defense shift is great. Still med kits are great too, and having 3 instead of 1 is also awesome. So this is a choose your awesome moment. As you always should have minimum 2 Supports you can grab one of each. As a personal preference I tend to favor field medic, but a med kit is an inventory slot you have to spend and field medic tends to mandate one. Now having more options is good, but so is having more healing. A pure utility Support can have Chitin Plating and an Arc Thrower, or Nano-Fiber Vest and a Scope. Thus make your choice not based on smoke alone, but on flexibility.

Lieutenant

Revive vs. Rifle Suppression

Chances are that you are screwed if you are relying on Revive. Whereas Rifle Suppression can help keep you from being screwed. The choice is elementary, my dead Watson. If you find yourself favoring Revive, then you might want to have multiple Field Medics instead and keep your soldiers HP topped off at all times. Revive

Captain

Dense Smoke vs. Combat Drugs

It is another Defense/Offense choice. Combat Drugs give +20 Aim bonus too (not listed). So in a tough situation will you protect you soldiers with a stunning +40 Defense shift that turns no cover into High Cover, and High Cover into immunity to being shot? Or annihilate X-rays with additional +20 Aim and +10 crit chance? Tough choice, but I prefer not getting hit. One thing to keep in mind is aliens benefit from smoke too, so don't let melee aliens get all up in your smoke business.

While Dense Smoke, maybe combined with Smoke and Mirrors, might seem like a near-immunity to the aliens' Plasma blasts, it carries a catch. Starting from the 3rd month and the appearance of Mutons, aliens will carry Grenades. Every alien that can throw a Grenade (with the sole exception of the regular Muton) also has the Bombard ability, meaning it can throw it real far and get you nearly everywhere. The thing is, Grenades never miss. So, when the X-Rays see their chances to hit are too low for their liking (like trying to hit someone standing behind full cover and in Dense Smoke), they will lob Grenades at you. This may not be a problem on Easy or Normal difficulty, as they will rarely do that on those, but on Classic and Impossible, you can expect Grenades flying your way pretty much at every opportunity.

So what, you say, that's just 5 damage, as opposed to taking 10+ from a Heavy Plasma crit? Yeah, sure... but think about this: Mutons and Heavy Floaters come in packs. If one thinks you're too hard to hit, so do the others probably. Well, 5 damage from one Grenade suddenly turns to 10 or 15. Of course they will try to catch as many of your soldiers in the blast radius as possible. Another point is that one Grenade-lobbing alien can set up perfect shots for its pals. Grenades destroy cover. Meaning after the first blast your +80 defense falls to +40, which is a pretty easy shot for any high-tier X-Ray. The only cover elements that an withstand an Alien Grenade blast are some of the objects inside UFOs. The perfect disaster scenario here is when two of you agents have taken cover on the sides of a single doorway, covered with smoke. A Grenade flies in and blam! - they are suddenly out in the open, with only the smoke providing protection, plus they've got 5 fewer HP each. In the mid-game on Classic or Impossible, this can mean assured death from Plasma crits for both of them.

This, by the way, is true for any AoE attack, like the Cyberdisc's Death Blossom, the Ethereal's Rift, or the Sectopod's cluster bomb (at least you can run away from that).

This taken into account, it may be a better idea to take Combat Drugs instead, and have a better chance of picking the aliens off with increased Aim and crit chance.

Colonel

Savior vs. Sentinel

Do you want to heal or harm? What kind of question is that! This is XCOM. You want to harm those X-Ray scum. Now don't get me wrong, healing 10 points in one charge is awesome, but shooting twice on Overwatch is even better. With Improved Medikits you should be healing 6 per charge anyways, and if you went with the medical route you can still top off the squad without worry. One of the most important things about sentinel is that it solves the problem of Overwatch overkill. The ability triggers a second Overwatch attack only if the first fails to kill the target, thus preventing those embarrassing moments where your squad all open fire on a floater and blow him to the moon, only for a Muton to wander unchecked into High cover and crit your prized soldier in the face.

Equipment

Simple enough. Get Skeleton Suit first, then upgrade to Ghost or Psi depending. I have already gone into a lot of detail as to why Ghost Armor is the best armor. A Support wearing it can traverse 13 squares on one move. A dash from another class in Heavy armor is 14. This is silly amounts of mobility. In terms of guns you have the choice of Plasma or Light Plasma. I find that while Light Plasma and a Scope is great early and can be obtained fast, it is offensively too inferior to use. Go for the big numbers and get a Plasma Rifle. Still one thing should be mentioned. Supports get a great return on investment in terms of lasers. The basic Assault Rifle allows them to one shot all the low tier enemies.  In terms of secondary items go with what you feel. Medikit, Scope, Chitin Plating, Arc Thrower. The important thing about Supports is that they are flexible and should never be bound to a single setup.