Soldier Skills & Equipment Guide (EU2012)

For descriptions of specific skills, see Abilities

Introduction

When choosing abilities, 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 a clear cut example of this: nearly all of its choices are between increasing the offensive or the defensive capabilities of the unit. The result of your choices can be a frontal assault & breach unit, a defense-oriented flanking unit, or a blend of the two. Additionally, the unique Flush ability can force an enemy out of cover, offering some utility to your squad.

Generally, the strength of these options depends on your style and strategy, and individual abilities may be stronger or weaker depending on the map and enemies present. Some of the recommendations provided here 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 options in the skill tree that are clearly false choices. Though they may seem roughly equivalent, 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.

Assault

Assaults are the only class that has a choice between primary weapons (shotguns vs. assault rifles). Because of this and the broad applicability of their individual skills, they don't necessarily have clear cut build paths. Shotguns offer damage values identical to sniper rifles -- albeit with lower crit chance -- and with the right abilities can enhance this to make the Assault the most damaging unit in the game. Assault rifles trade damage for the safety of distance (and typically better cover, as a result), and defensive skills can further improve the soldier's ability to protect himself and his squad. All Assaults, however, provide the toughness and mobility to form a backbone for your squad, and bringing 2 (or more) will become typical as you expand your squad size.

Abilities

Corporal

Tactical Sense vs Aggression

Here starts the divergent options of offense vs. defense. Which one you choose should be dependent on how you are planning to equip and play the Assault, choosing to accentuate strengths or shore up weaknesses. Generally though, shotgunners will prefer Tactical Sense and riflemen will want Aggression.

Tactical Sense's defense bonus is powerful for both riflemen and shotgunners, and its value increases exponentially with other defense boosts such as cover, Ghost Armor, and smoke grenades. Shotguns do a ton of damage by themselves, so Tactical Sense can be a great pickup to help you survive the stupid situations that result from charging in using Run and Gun with a short range weapon.

Aggression similarly offers value for both weapon types. Assault rifles have low base damage and thus benefit from an easy way to increase that output without jeopardizing their cover. Shotguns do gain more damage from critting than assault rifles, and you probably don't want to charge up to enemies, empty your weapon on them, and not kill them. Bear in mind, however, that flanking is easier to achieve up close and provides a 50% bonus to crit chance. That large swing has the potential to make this somewhat redundant.

Sergeant

Lightning Reflexes vs. Close & Personal

These skills both address your ability to close in on enemies, either in getting there safely or finishing them once you're there. Lightning Reflexes is generally preferable, but shotgunners should consider Close & Personal as well.

Lightning Reflexes is an amazing skill, and you will want at least one unit with it on your team. The ability to safely "clear out" Overwatches is good all the time, and it's particularly great when dealing with escort missions and Sectopods. While you can always count on XCOM to teach you that probability is a fickle mistress, Lightning Reflexes will always be there to tuck you in at night and feel safe.

Close & Personal continues the trend of making Assaults crit-monsters, and combined with Aggression will give you a 40%-60% bonus to crit chance before taking either weapon stats or flanking into account. If you can get in close, your target is going to need to be cleaned off the walls with a spatula. However, as riflemen generally will keep their distance, this will be of dubious value for them. And similar to Aggression, shotguns have high damage, good crit chance, and love flanks by default -- this may prove to be overkill.

Lieutenant

Flush vs. Rapid Fire

Welcome to the first false choice of the Assault tree. Enjoy your Rapid Fire and have a nice day. Both choices increase your ammo consumption, so if you're using them frequently, consider the Ammo Conservation foundry project.

Rapid Fire adds tremendous killing power, and as we say in the business, "death is the best debuff." Taking a pair of shots - even at a 15% penalty - will almost always improve your chance to hit the target once, and gives you the possibility of hitting twice. This is one of the most broadly useful skills in the game, and is never a bad pickup.

Flush is... nuanced. It carries three flaws that make it unusable on most missions:

1. It costs 3 ammo, so you can't use it every turn and will reload more often than Rapid Fire -- assuming you have enough ammo left to use it in the first place
2. While it drives the target out of its current cover, the enemy could go to different cover or break sight range completely. Destroying the target's cover with explosives will almost always be preferable. (And Rapid Fire may destroy the target's cover with the first shot, improving accuracy on the second.)
3. The shot has significantly improved accuracy, but at reduced damage. Sure, it will take out an enemy on its last legs, but the two shots afforded by Rapid Fire also offer higher effective accuracy without a damage penalty.

There's still room for Flush to set up plays for Snipers who don't quite have line of sight, Heavies who are going to be launching rockets and hope to catch one more enemy in the blast zone, or other Assaults itching for a Close Combat Specialist crossfire. In most cases, however, you will struggle to take advantage of the movement Flush triggers.

Captain

Close Combat Specialist vs. Bring 'Em On

Continuing the earlier theme, the Assault tree has a lot of great options. This is a choice for both weapon types.

Close Combat Specialist is a godsend against charging melee, the poor fool that wanders through a door you are next to, or any close range engagement. Shotgunners will see this trigger more frequently, and thus have a little more use for it than riflemen.

Bring 'Em On, in contrast, has no range requirement but offers tremendous synergy with the other crit abilities available to an assault. If you took Aggression and/or Close & Personal, this is a chance to make large dividends on that decision. Riflemen with upgraded S.C.O.P.E.s will similarly get some extra mileage. Just remember that the bonus is based on enemies that the squad can see, so you may want to have this unit attack before your other soldiers in order to maximize its value.

Colonel

Resilience vs. Killer Instinct

Again, both choices are great options. This is similar to the choice of Lightning Reflexes vs. Close & Personal in weighing defensive certainty versus major killing power boosts, and should be considered for both weapon types.

Resilience will make you a brick. Immunity to crits take luck out of the equation and put shotgunners at less risk of being taken out in one fell swoop as they charge in for kill shots. Remember that you can briefly duplicate the effect (and more!) with Combat Stims, however.

Killer Instinct is the blood-soaked cherry atop the murder sundae that is the critical hit-focused Assault. In concert with Bring 'Em On, your critical hits can exceed 20 damage, regardless of weapon type. Even without it, 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

Weapons: Upgrading your weapons is a fairly significant concern for Assaults, as a base Assault Rifle won't reliably kill even Sectoids or Thin Men. Luckily, riflemen get some freebies from capturing enemies. No such luck for shotgunners, who unfortunately are also 1 step further down the tech tree. If Light Plasma Rifles are the most advanced assault rifles you have, give them to Assaults (rather than Supports) in order to offset some of the penalty from Rapid Fire. Shotgunners will also appreciate a decent pistol if you have any to spare, though this is typically a lower priority than giving one to your Sniper.

Armor: Assaults will be a major part of your front line regardless of their weapon and should get first choice of the most advanced armor you have. Ghost Armor is typically your best bet late game, as the defense bonus will generally serve you better than the few extra hitpoints of Titan Armor. Shotgunners in particular will love Ghost Armor's movement speed bonus and invisibility as they charge into the fray. The +100% crit chance you get from firing while invisible also has great synergy with Bring 'Em On and Killer Instinct.

Item: Any item is a viable choice on an Assault, excepting the Medikit. Their position at the front line makes them good grenadiers and good secondary users of the Arc Thrower if your Support's hands are full. If you don't need either of those, Nano-Fiber Vests or Chitin Plating are great for shotgunners, and riflemen will appreciate a S.C.O.P.E., especially with its foundry upgrade. Keep an eye on your unit's Will and use Mind Shields if necessary.

Heavy

Heavies are the class with the starkest difference between builds. On one hand, you have an explosives specialist capable of putting out major damage in an area, making big plays to pull your squad out of the fire when XCOM decides to be... well, XCOM. On the other hand, you have a Suppression expert that crowds out the Support for his job.

As for the Heavy himself, he's in an interesting place. Though all soldiers begin with the 65 Aim, Heavies gain significantly less through promotion than their peers. In contrast, his machine gun deals high damage, on par with a sniper rifle or shotgun. These facts, combined with his rocket launcher, make him a terror in the early game but potentially less reliable (and thus less relevant) as it progresses. Between their poor Aim and inability to fire rockets after moving, Heavies are the class most hampered by mobility.

In light of this, beginning players may find explosives-centric heavies preferable. Suppression-focused heavies take a while to come into their own and depend on their squad to provide killing power once they do. Explosives Heavies are somewhat more straightforward to play, and they themselves provide more firepower to carry your team before it becomes a well-oiled x-ray-killing machine.

Abilities

Corporal

Bullet Swarm vs. Holo-Targeting

Explosive Heavies should grab Bullet Swarm. Suppression Heavies may prefer Holo-Targeting in the long run, but also benefit from Bullet Swarm.

Bullet Swarm gives you massive tactical flexibility. It allows for Fire and Move, Fire and Reload or Fire and Fire. In particular, shooting twice ends up yielding a statistically better chance of hitting a particular alien than Holo-Targeting him and ordering the rest of your Rookies to open fire. Also, since the machine gun only has 3 rounds, even if you take Suppression, you need Bullet Swarm to Suppress two rounds in a row. Finally, firing twice gives the Heavy two chances to destroy his target's cover; in this event, he has just granted your squad more than the benefit of Holo-Targeting.

Holo-Targeting is, by itself, not very good. At all. Only take it when you plan on taking Suppression. And even then, don't expect it to do a tremendous amount of work for you until a few promotions down the road.

Sergeant

Suppression vs. Shredder Rocket

This is it. This is the choice. Shredder Rocket for Explosive Heavies, Suppression for Suppression Heavies.

Shredder Rockets are handy throughout the game. On all difficulties except Impossible, they deal enough damage to one-shot Sectoids, Thin Men, and Hoverers, making them essentially just another rocket when you first get them. Rockets are great, so that's fine. Later on, the Shred effect helps with high HP targets. Also, the set damage provided by explosives can help set up aliens for capture, as dubious as "shoot a slightly weaker rocket at him" seems as a strategy.

Suppression is a handy utility skill that applies Holo-Targeting and can sometimes convince the AI to sit on its hands and do nothing -- not move, not shoot, not Overwatch, not throw a grenade. Even when the game decides to actually react, it's helpful in dealing with enemies in good cover that the Heavy wasn't going to hit anyway, especially if a squadmate is in danger. Do note that Supports can gain this ability as well.

Lieutenant

HEAT Ammo vs. Rapid Reaction

Similar to the Corporal choice, both Heavies like HEAT Ammo, but Suppression Heavies can consider Rapid Reaction.

HEAT Ammo deals extra damage to robotic opponents. Put simply, in XCOM, robots are the devil. Anything that hastens Cyberdiscs and Sectopods to their circuity grave is awesome. This is also one of few ways to scale your explosives damage, as the Blaster Launcher cannot be obtained until beating a difficult mission type very late in the game. Also, you get to decide what you think HEAT stands for. Heavy Explodes All Tech? (Doubles as a battle cry.) HEAT Explosives Are Thorough? (Bonus points for recursion.) The power is yours.

Rapid Reaction is in some respects similar to Holo-Targeting: not very good on its own but useful with the right setup. The trigger being a successful reaction shot hurts this significantly. Reaction shots are made at a 15% penalty to hit, and we've established that Heavies are not good shots to begin with. So, in order for this to actually benefit you, you just need to convince an enemy to move when & where he shouldn't, then hit two low-percentage shots with your least accurate soldier. Yeah. There is, however, room for shenanigans involving the Assault's Flush ability, as well as Danger Zone and Mayhem later in the Heavy's tree. Just make sure you get the Ammo Conservation project done in the Foundry or you will find that this is a fantastic way ineffectively empty your magazine.

Captain

Grenadier vs. Danger Zone

Both types of Heavy like Danger Zone. Explosive Heavies should also consider Grenadier.

Grenadier locks you into a single item to take advantage of it, but grenades are admittedly useful. Just make sure you upgrade to Alien Grenades in the Foundry if you go this route. Also consider whether you typically have grenades on any of your other units. If not, giving up a wildly-inaccurate Heavy shot to hurl a grenade is not a big sacrifice by any stretch, and the rest of your squad will thank you for blowing the enemy's cover. Similarly, if you think you'd rather Kool-Aid Man through a wall instead of using the door, doing it with a grenade beats burning a rocket on it.

Danger Zone, first and foremost, will get the Kenny Loggins song stuck in your head immediately. Beyond that, Explosive Heavies will love having a bigger boom, but it's Suppression Heavies that make out like bandits. AOE Suppression requires on fairly particular enemy positioning, but when you can manage, it's a great boon. Perhaps more importantly, you also get to apply Holo-Targeting and Rapid Reaction to the whole group, turning a pair of not-so-great skills into potentially decent add-ons.

Colonel

Rocketeer vs. Mayhem

Explosives Heavies will want Rocketeer. Suppression Heavies should take Mayhem.

Rocketeer boosts your overall damage output while taking away some of the nerves you get when thinking about whether now is really the best time to shoot your one, single rocket. While Mayhem does add some damage to your rockets, Rocketeer ultimately amounts to more damage and gives you more control in how you apply it.

Mayhem is the grand finale for the AOE Suppression show. Suppression becomes a reliable way to damage enemies (which the Heavy otherwise needs to expend rockets for) and makes up for the fact that, face it, you weren't going to hit them anyway. The extra damage on your rockets is a nice side benefit, and it can be a nice consolation prize if you skipped HEAT ammo.

Equipment

Weapon: More than any other class, the Heavy doesn't need primary weapon upgrades. By all means do so if you can spare the resources, but keep in mind that rockets, grenades, and suppression all ignore your machine gun. Moreover, with the high base damage of the weapon, Heavies can one-shot Sectoids, Thin Men, and Floaters on Classic, mitigating the need to upgrade to Laser.

Armor: Heavies will typically be near the front of your group, as they need to advance and sit still in order to put rockets where they need to be. As a result, Armor is a fairly big priority for Heavies, and they should be considered after Assaults for cutting edge suits if you can't outfit your full team. Skeleton Armor and Ghost Armor eliminate all mobility issues, with the invisibility from Ghost Armor being particularly helpful in setting up rockets or flanks, counteracting the low Aim. Titan Armor, despite being the "heaviest," is not actually a great choice due to the aforementioned mobility consideration.

Item: If you went Grenadier, grab a Grenade. Otherwise, S.C.O.P.E.s can offset the Heavy's low Aim if you find that you're using your gun a lot. Heavies also make decent carriers of Medikits if your Supports for some reason don't have enough, as their combat effectiveness drops after they run out of rockets.

Sniper

The Sniper works exactly as you would expect: long range, high damage, low mobility engagement. Depending on the level and your position, a Sniper will either be an unstoppable murder engine snuffing out at least one enemy every round, or he'll spend most of the time running around useless trying to get a line of sight. Building a sniper revolves around managing their killing power while stationary versus their complete lack of it while on the move. Despite this, there are a number of no-brainer choices in their ability tree, greatly limiting the viable customization.

Abilities

Corporal

Snap Shot vs. Squadsight

This is the biggest trap choice in the game. Take Squadsight in all circumstances.

Squadsight is the ability that allows your Sniper to actually snipe. In short, a soldier's ability to target enemies relies on the range of his weapon (100 for sniper rifles), having line of sight to the target, and being within vision range of the target (27). Squadsight removes the last requirement, allowing the rest of your squad to spot for your sniper as he relaxes three-quarters of the level away. Squadsight allows you to make use of high ground more effectively (further amplifying your killing power), cover your squad as they advance, and actually hit anything, ever.

Snap Shot, in theory, is designed to help the Sniper contribute on maps in which obtaining line of sight is difficult. However, the accuracy penalty drops the Sniper's Aim from the best in the game to noticeably worse than both Assaults and Supports. Furthermore, sniper rifles suffer from an additional Aim penalty in close quarters. The result is that you need to position specifically for a mid-range engagement -- imposing its own positional inflexibility -- and forcing you to augment the Sniper's defense accordingly. And even in those ideal circumstances, the Aim penalty means that this is still strictly worse than an Assault with an assault rifle. There are other abilities in the Sniper tree to help him breach with the team. If that's a concern, consider them.

Sergeant

Gunslinger vs. Damn Good Ground

This is a question of minimizing weakness or maximizing strength. Damn Good Ground is generally better, but Gunslinger merits consideration.

Damn Good Ground rewards you for parking on high ground and blasting away, which is what you want to be doing anyway. This helps the Sniper as your go-to for getting rid of a high priority target, and partially makes up for the fact that you are generally shooting into cover. You should be shooting from high ground more often than you shoot your pistol, and Damn Good Ground accentuates that.

Gunslinger is the ability you want if you need a Sniper that can scoot and shoot. You won't be a force to be reckoned with in close range, but you'll contribute. The pistol projects in the Foundry can further improve this, making it a fairly effective close range option with the right investment.

Lieutenant

Disabling Shot vs. Battle Scanner

Two moderately helpful utility options make this something of a tossup. Go nuts.

Disabling Shot is a nice option for when blowing a hole out the back of a target's head isn't an option. Be aware that is generally only the case when your weaponry isn't up to the task of the foes you're facing, you're attempting to capture an alien, or one of your units has been mind controlled. There is a small Aim penalty attached to this, and the attack does reduced damage; make sure you don't accidentally kill the target.

Battle Scanner is the best scouting tool in the game this side of Ghost Armor. Scanning does not trigger enemies to take cover, so you can use this to get the jump on a pack of aliens with a sniper round or rocket to the back of the head. Its limited range means that the Sniper will not be in range to use it on open maps where he's miles away from his team, but it can be very useful in close quarters, especially with melee enemies afoot.

Captain

Executioner vs. Opportunist

This is something of a toss-up, but Opportunist is generally better.

Executioner is nice when a wounded enemy absolutely needs to die, but two things hold it back. First, the bonus itself is fairly minor on a class that already has great Aim. Second, snipers are generally able to kill targets in one shot (or Headshot), which will keep the trigger condition from being relevant much of the time. Still, the RNG is fickle enough that this is not a wasted skill. Pushing you up to 100% to hit against a major enemy is never a bad thing.

Opportunist improves your ability to cover the rest of the squad during Overwatch, helping mostly when aliens decide to patrol into your team blindly. With the range on Sniper Rifles, this ends up being a nice bit of coverage. Enemies triggering Overwatch are frequently in the open, partially reducing the need for this, but it's still an improved chance to save you time during your actual turn, which ultimately earns it the nod.

Colonel

In the Zone vs. Double Tap

The last level is once again the choice between a great ability and a fairly bad one. You want Double Tap.

In The Zone is streaky, when conditions are right. The problem is, conditions rarely are. Because your Sniper will be so far back and stationary, he will basically never flank anyone. The only time In The Zone is likely to work is when you destroy a group of enemy's cover with explosives, and in that case, you've already spent explosives on them and can probably finish them off with your rank and file.

Double Tap, conversely, is both powerful and broadly applicable. For comparison, this is Rapid Fire (Assault) with a shorter cooldown, the ability to retarget if your first shot results in a kill, and no Aim penalty. You will never ever regret having it.

Equipment

Weapon: You can technically get by for a little while without upgrading your sniper rifles thanks to their good damage, high crit rate, and Headshot. However, a Sniper that can't kill his targets in a single shot is not a very good asset to the squad, so you will want to keep up with tech here. Snipers also benefit from pistols much more than other classes, give them your best for those turns that they can't sit still.

Armor: The best defense is a good offense. The second best defense is being too damn far away. Snipers have both of these, so you generally don't need to prioritize armor. Skeleton armor will help get you to a good position, and the defense bonus stacks nicely with Low Profile. Archangel is your go-to for the end game.

Item: Get a S.C.O.P.E. and call it a day.

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.

Psionic

Psionics are clearly an asset to any class. Shotgun Assaults can use psionics to engage at medium range when it's not possible for them to Run & Gun for a close range shot. Snipers can use psionics as a weapon after moving. Heavies can use psionics as a crutch to make up for their terrible aim at high levels. Supports in a way gain the least from psionics, but their Deep Pockets ability allows them to carry a Mind Shield, which gives them fantastic offensive psi ability hit chance.

Abilities

Psi Inspiration vs Psi Panic

Psi Panic is a dubiously useful ability. It causes the unit to panic immediately upon use and then skip the next turn. The problem is that often the unit's panic action will be to take a shot at you, which isn't a massive improvement on what it would have done had you not panicked it. Sometimes the unit will do something else like hunker down or run away, and it does prevent the use of any special abilities like grenades.

Psi Inspiration gives a +30 boost to Will for 2 turns and removes Mind Fray and Panic. The most important thing this ability does that isn't mentioned is remove the Fallen Comrade Will debuff. This is very useful when using Mind Control, because mind controlled aliens dying will cause this debuff and you'll want to get rid of it so it doesn't hamper your morale and psi abilities for the rest of the mission. The Will bonus will buff your soldiers' offensive psi ability hit chance and defense against enemy psi attacks, making it a useful ability to use before breaching a room. Psi Inspiration can be used to level up to the next psi level quickly, because it can be used on spare turns when not in combat. While Psi Inspiration is an area effect ability, it only reaches two tiles, so can be a pain to get many other soldiers without forming your squad in to grenade bait formation. If in doubt, Psi Inspiration is the ability to take over Psi Panic.

Telekinetic Field vs Mind Control

Mind Control is easily the most powerful ability in the game in most encounters. While it's difficult-to-impossible to pull off against psionic enemies, they usually have non-psionic guards (Muton Elites in particular) who can be controlled. The only major enemies it doesn't help against are Cyberdiscs and Sectopods, though mind controlled aliens from a previous group will make for good cannon fodder for them. If in doubt, Mind Control is the ability to take.

Telekinetic Field is essentially a psionic smoke grenade. It is always centered on the soldier creating it, rather than being placeable like a smoke grenade, but it makes up for this by being much larger. It also gives +40 defence like a dense smoke grenade. The main use for this ability is to protect your squad from the attacks of a sectopod or cyberdisc if you have to finish your turn under its guns.