The Advanced Warfare Center grants a random portion of your soldiers a single random skill assigned at a random level to unlock for free on top of whatever they would normally get. Note that such bonus skills aren't unlocked retroactively (ie building the advanced Warfare Center won't cause soldiers to suddenly gain skills), but can potentially be acquired through the retraining function the Advanced Warfare Center conveniently provides. SPARKS and Psi Operatives are exempt; they're stuck with their own core skills. To be fair, they don't really need the support...

 The skills in question are largely skills available to your core four classes anyway, and indeed the primary rule for whether something is available or not is whether it's exclusively attached to the secondary weapon. If yes, it's not in the pool; no Pistol-related skills from the Sharpshooter, no Sword-related skills from the Ranger, no Gremlin-related skills from the Specialist, and... the Grenadier's one skill tied to their bonus grenade-only slot is also not in the list. Everything else? Toss it in! (Well, mostly)

 This includes some unintuitive cases, such as the Sharpshooter's Return Fire skill not being in the pool purely because the retaliation uses their Pistol in specific.

 The practical result is that almost the entire Grenadier kit and much of the Ranger's can show up on anyone, whereas the Sharpshooter and especially the Specialist offer little to the pool.

 A related caveat is that a class cannot get a bonus skill from its own class. A Specialist can't get a free Covering Fire; you don't have to worry about 'wasting' a level by taking a skill the soldier was going to get for free from the Advanced Warfare Center.

 There's also some special exclusions I'll get into as we get to them.

 The following is the specific list, with some commentary from me:

Ever Vigilant
At the end of the squad's turn, the soldier enters Overwatch if they took no non-movement actions.

Note that a Sniper with Ever Vigilant will go into Pistol Overwatch, not Sniper Rifle Overwatch, much like how Threat Assessment gifts them a Pistol Overwatch shot.

 Rangers, meanwhile, are flat-out forbidden from getting Ever Vigilant to prevent conflict with Deep Cover.

So it can only actually roll on Grenadiers and Sharpshooters.

 For Sharpshooters, Ever Vigilant partially helps make up for how their Sniper Rifles tend to leave them dragging behind the team, letting them Dash to catch up the team without completely abandoning the benefit of taking a free shot at a pod that wanders into your team. It's not particularly great for them, but hey, at least Pistol shots are completely free. You're not even burning ammo on them, after all. It can make it a little more viable to try to take advantage of the Sniper Rifle capabilities in particular, since them falling behind the team isn't quite so problematic.

 For Grenadiers, Ever Vigilant can be particularly useful for missions with time pressure and no starting Concealment, such as VIP Extraction and Retaliation missions. In conjunction with a Phantom or Conceal-capable soldier blazing a trail, you can advance aggressively while still getting a first shot in on pods that stumble into your group. As Grenadiers have natural access to Shredder, being able to get reliable first strike is particularly useful with them. Even outside those particular kinds of missions, it can be pretty good, and it goes particularly well with Salvo, as taking advantage of Salvo tends to lead to the Grenadier falling behind a bit.

Covering Fire
Overwatch can trigger on most non-movement actions, in addition to movement.

Covering Fire is one of the worse possibilities to roll: in the vast majority of situations where Covering Fire does anything it's because you made a bad decision in the first place. On an actual Specialist, Covering Fire can at least be combined with Ever Vigilant to create situations where Covering Fire triggering isn't due to bad decisions on your part, or combined with Guardian to gamble on getting extra shots. On the other three classes, it's just plain bad.

 There's a few skills that are arguably even worse, at least on specific classes, but I genuinely don't understand why Covering Fire is even in the pool in the first place.

Guardian
Each time an Overwatch shot hits its target, there is a 50% chance the soldier will remain in Overwatch.

While I'm not a fan of taking Guardian on Specialists, getting it for free is actually plenty good. It's especially nice to have a Grenadier roll it, so they can spam Shred and Holo Targeting if you get lucky, particularly in an Overwatch ambush. It's probably least impressive on Sharpshooters, in part because if you're serious about leveraging a Sharpshooter for Overwatch fire Kill Zone covers that utility without requiring the RNG cooperate, but it can still potentially help in situations you were going to use regular Overwatch so there's certainly worse things to roll.

 Getting it on a Ranger tends to be borderline pointless since they're generally fairly poor at Overwatch fire, particularly if you consistently leverage their Shotguns, but hey, you can get lucky in an Overwatch ambush or something. There's worse possibilities out there. Like Covering Fire.

Blast Padding
+1 Armor, and explosives do only 34% of normal damage to soldier.

Generally disappointing to get on a Sharpshooter you've geared to snipe with, but otherwise... there's more amazing options out there, but Blast Padding is certainly never bad. Rangers in particular appreciate having improved survivability given they're at their best with fairly reckless play, but it's also nice to have it that bit more likely your Specialist will survive to be able to patch up everyone else.

Shredder
Primary weapon has Shred equal to weapon's tech level.

This can make your team a lot more flexible, potentially letting you not take a Grenadier or SPARK at all into an Armor-heavy mission because you have sustainable Shred anyway.

 Sharpshooters getting Shredder tends to be a bit lackluster. It doesn't affect their Pistol, which is where a lot of their best qualities are concentrated, and both Death From Above and Serial are predicated on the idea of landing killshots with the Sniper Rifle, a scenario in contradiction of softening the enemy up with Shred. Kill Zone is the only Sharpshooter skill that can make Shredder fairly appealing, and even then it's only really dramatically useful in the initial Overwatch ambush. I tend to consider Shredder on a Sharpshooter a dud.

 Specialists getting Shredder is very useful. They're particularly reliable at landing initial Overwatch shots, softening up pods that stumble into your team before your turn properly rolls around, Guardian Specialists can potentially spread Shred around which can be useful if you activate a pod with multiple decently-Armored targets, and support-oriented Specialists can often pull off their key duties while still taking potshots to leverage Shredder. Specialists who take the offensive lane don't like Shredder as much, since the offensive lane's actions consistently end the turn without providing an opportunity to shoot at enemies, but overall it's pretty great for a Support to roll it.

 Rangers getting Shredder isn't a great fit with their multiple skills that encourage landing killshots in particular, but unlike Sharpshooters it can act to make them a little less overly-specialized. A melee build Ranger who rolls Shredder can help soften up Sectopods and Gatekeepers, instead of getting frustrated by how trying to melee them is a terrible idea. It's also decently synergistic with Rapid Fire for opening up the hardest targets for the rest of the team.

Chain Shot
Fires a shot at -15 Aim. If that shot hits, immediately follows-up with another shot at -15 Aim. 3 turn cooldown.

This is nifty to get on a Ranger, since they're very effective at getting in close and Shotguns have disproportionate Aim boosts for closing, potentially completely offsetting the Aim penalty. It's technically inferior to their naturally-available Rapid Fire, but it's pretty easy for Rangers to get into situations where Chain Shot's only disadvantage is having a cooldown. This is especially nice if you're a fan of Reaper, allowing you to get approximately the benefits of Rapid Fire without sacrificing Reaper.

 The alternative possibilities are not so hot.

 Sharpshooters can't perform Chain Shot at Squadsight distances, nor perform a Pistol Chain Shot, severely limiting its utility for them, and since they don't get Aim climb it's a lot harder for them to create situations where their hit rate is 100% with a Chain Shot. It can be okay to use for opening an Overwatch ambush, but beyond that it's pretty terrible.

 For Specialists, it's a little less terrible, but still not a great fit to what Specialists tend to do best. They're not great at getting flanks or closing in on enemies prior to firing, since they have incentives to eg Aid Protocol, at which point moving and firing isn't an option anymore, their base Aim isn't so hot, and Rifles are the weakest weapon anyway so getting two shots out isn't as great as getting two shots with a Grenadier or Ranger. There's not really anything you can do to have a Specialist leverage it better, either, aside attaching a Repeater I suppose.

Holo Targeting
Firing your primary weapon at an enemy marks it until the start of the soldier's next turn, adding +15 Aim to all following attacks at that target.

Note the 'primary weapon' qualifier. No combining it with the Sharpshooter's assorted Pistol skills. Particularly disappointing that it doesn't combine with Face-Off.

 Nonetheless, Holo Targeting is one of the generally best skills to roll for any class. You can't stack Holo Targeting, so it's not ideal to have literally the entire squad roll Holo Targeting, but beyond that it's just plain good.

 Medical Specialists tend to particularly appreciate it, since hitting things with their gun tends to be their weakest, least reliable contribution. Being able to tag a target for the benefit of more lethal soldiers makes it more productive to take potshots. Specialists specialized in the offensive portion of their tree will get less consistent use out of it, but it's useful to have regardless, especially in longer missions where they'll run out of charges on their Gremlin-based attacks.

 Sniping-oriented Sharpshooters appreciate being able to contribute even if they're further out than you'd prefer, and Kill Zone Sharpshooters in particular enjoy getting to tag a bunch of targets in an Overwatch ambush. Pistol-oriented Sharpshooters can still occasionally get use out of it, too, though overall it's a bit of a dud for them.

 Rangers getting Holo Targeting is a bit of a covering weaknesses thing, like Shredder but from a different angle, providing a way for them to semi-reliably contribute against Gatekeepers and to a lesser extent helping against Archons, and is also decently synergistic with Rapid Fire as the second shot will in fact benefit from the Holo Targeting the first shot attached. Rangers are sufficiently biased toward outright killing things Holo Targeting is arguably a bit wasted on them, but you'll periodically get use out of it regardless, and the ability to take a potshot with a Shotgun at a distance to Holo Target makes Rangers a little more versatile without specifically gearing for versatility.

Hail of Bullets
Expends 3 ammo, but is guaranteed to hit the target. Cannot crit. 5 turn cooldown.

It's too bad all these special shot actions don't get to extend to Squadsight distances on Sharpshooters, as Hail of Bullets would be nice for letting a badly out of place Sharpshooter land a clutch shot at extreme distances completely reliably. As-is, this is very niche on a Sharpshooter. It's not like you get a Pistol version, either, which would be legitimately pretty decent. Ah well.

 That said, it does have one use: Hail of Bullets doesn't require two action points to fire, even when used by a Sharpshooter, and thus can be used as an ammo-intensive way for a Sharpshooter to move and shoot every once in a while. This is still pretty niche, but less bad than it could be.

 Otherwise, Hail of Bullets tends to actually be better on non-Grenadiers than on its home class. Rifles and Shotguns have enough base ammo to eg fire off an Overwatch shot and still be able to immediately Hail of Bullets without needing an Expanded Magazine or Auto-Loader to make it happen, unlike Cannons, for starters.

 For a Specialist, Hail of Bullets can be a lifesaver in the right situation. Make sure to give them an Expanded Magazine and/or Autoloader so they actually have the ammo when you need it, but being able to force a full hit is fantastic. Also keep in mind that you can't use it with the Bolt Caster, since it can never have more than one ammo. Also remember that Hail of Bullets can be used to ignore Dodge, which can be useful in situations where you actually have a decent but non-perfect chance to hit and want to be sure the hit actually does full damage. This is particularly relevant if you're fighting a Codex, since a Graze can result in them splitting unexpectedly.

 Rangers particularly appreciate how Hail of Bullets can be used to force a Shotgun hit even at a distance, and also appreciate how it makes it easier for them to contribute against Gatekeepers and Archons, who are both otherwise somewhat problematic for Rangers to cope with. You're still usually going to be best off trying to pursue flanks, often making Hail of Bullets a bit of a waste, but in those situations Hail of Bullets helps it really helps.

 Do note that the inability to crit is more of a weakness as an Advanced Warfare Center skill than as a Grenadier skill. Sharpshooters and Rangers both normally have innate crit chance, Rangers are particularly encouraged to use Laser Sights and Talon Rounds for more crit chance, and both of them wield weapons that can suffer accuracy loss; using Hail of Bullets at long range with a Ranger or short range with a Sharpshooter to overcome the accuracy penalty is missing out on damage you 'should' be getting.

 For the Specialist it's not too big a deal, but still overall more relevant than for a Grenadier, particularly if eg you like to give your Specialists crit boosters because they can get crits during Overwatch.

Rupture
Expends 3 ammo, but is guaranteed to crit on a successful hit and the target permanently suffers from the Rupture status, which causes all following attacks to do an additional 3 damage per hit. 3 turn cooldown.

Rupture is particularly excellent on Rangers, since Shotguns have especially high crit damage. In fact, Rangers are probably better users of Rupture than Grenadiers, since Shotguns also have more base ammo than Cannons! In conjunction with how effective Rangers are at arranging highly accurate shots, Rupture is quite reliably useful on a Ranger. It's also convenient how it's best used against extremely durable targets like Gatekeepers and Sectopods, since normally Rangers are a little lackluster against those targets; Rupture lets them support the rest of the squad taking these tough targets out quite effectively.

 Specialists are okay users of Rupture. They're not so great at getting flanks and whatnot, but Rifles have the same unusually high ammo as Shotguns so it's a little easier to slip in a Rupture, and Specialists are best off supporting the rest of the squad rather than being a primary source of damage so a Rupture is a useful way for them to spend their time if they can land it.

 Sharpshooters are extremely difficult to get to use Rupture. As usual, it can't be fired at Squadsight ranges or applied via Pistol, so it's only really okay for opening an Overwatch ambush. Which basically requires you arrange to have your Overwatch ambush hit something particularly durable to really be worth the bother. And Sharpshooters really resent ammo-intensive abilities if you're not assuming Autoloaders and Expanded Magazines since reloading means not getting a chance to fire their Sniper Rifle in the turn they reloaded. It's really too bad, because Rupture really seems like it should be a good fit to Sharpshooters. Alas.

Salvo
Using a Heavy Weapon or throwing a grenade as the first action doesn't end the soldier's turn.

Salvo is a bit annoying to roll on your medical Specialist who doesn't really want to give up Item slots to heavy armor or a grenade, but for more offensively slanted Specialists it's actually pretty darn good. Being able to lob a Blaster Launcher shot before using Combat Protocol or hacking a robot or whatever is a pretty nice combination, and while offensive Specialists would prefer to have a Skulljack for the Hack bonus it's not really a big deal to give up for a grenade and Heavy Weapon.

 Rangers can also appreciate Salvo a surprising amount. You can get greater turn value out of an Overwatch ambush by having a Ranger toss a grenade or Heavy Weapon shot and then after the enemies have run for Cover the Ranger burns their other action point on Slashing something, and in an Overwatch ambush it's pretty easy to get close enough to land the grenade on-target even without a Grenade Launcher helping. Even after Concealment has been broken, it's not unusual to end up in a situation where a grenade can be tossed without sacrificing a Slash, and with Run And Gun a Ranger can potentially unload their Heavy Weapon and lob a grenade and fire their Shotgun into something, which can be fantastic in an Overwatch ambush against a particularly nasty formation or just for pulling your team out of a bad situation.

 Sharpshooters... well, sniping-oriented Sharpshooters don't care for it overall, since burning an action point means no Sniper Rifle shot regardless, but Heavy Weapons can be useful for sniping Sharpshooters to give them a solid option in situations they need to move but where you still need them to do real damage, and Salvo increases their flexibility with Heavy Weapons a little bit. If you're backing them with Inspire-capable Psi Operatives, you may even be able to eg fire off a Blaster Launcher and then follow up with Serial to finish off the enemies you just blasted.

 Pistol-oriented Sharpshooters quite consistently appreciate Salvo. Sure, Quickdraw covers the 'do something aggressive without ending the turn' utility to some extent, but Salvo's added flexibility is still quite useful. Being able to open with a Heavy Weapon strike before following up with Faceoff is plenty effective, given that Heavy Weapons mostly means Shred and Pistols really need Shred support. With Salvo, a Gunslinging Sharpshooter can potentially end up in a bad situation without ready Grenadier support and salvage it on their own, as a particularly extreme example. Even in more ordinary circumstances, the added flexibility makes it easier to disentangle fights where you've gotten your squad in over their head. More flexibility is never bad.

 Salvo is one of my favorite AWC skills, honestly, since it tends to genuinely change how you think about tooling and using the soldier that rolls it.

Volatile Mix
Grenades do +2 damage to units.

This is... certainly not bad to have, but it's still vastly superior on an actual Grenadier. Rangers can occasionally make decent use out of Volatile Mix since they tend to be in the thick of things anyway, but Specialists are rarely in a good position and have strong Item pressures discouraging equipping grenades and Sharpshooters are even worse if you're using them to snipe. Even Pistol-focused Sharpshooters aren't particularly great at leveraging grenades.

 Generally a dud to roll, though not the worst dud.

 Do keep in mind it actually works on Flashbangs, though. If you roll it on someone, it can be worth considering having them cart around a Flashbang to leverage it. 2 damage in a massive blast radius is actually plausible to leverage for purposes like finishing off crippled targets. It won't have friendly fire, either! (Note that a Frost Bomb will have friendly fire if backed by Volatile Mix)

 It's too bad it doesn't expand the radius. If it did, it would at least make the recipient an okay backup grenade-carrier if eg your Grenadier isn't available for a mission due to injury and you want the Frost Bomb to have a non-terrible blast radius.

Aim
Hunkering Down confers +20 Aim to the soldier's next shot.

Note that the Ranger's Deep Cover ability does, in fact, trigger Aim. If you have a Ranger roll Aim, you may want to consider having them consistently carry a Rifle into missions; a Deep Cover Aim Overwatch will be quite reliable at hitting things in an Overwatch ambush so long as you're not eating the Shotgun's range disadvantage.

 Rolling it for Specialists and Grenadiers is a lot more situational. You can still set up Aim to benefit an Overwatch ambush if you're not under time pressure, but if you are under time pressure -which you usually are- you'll rarely get an opportunity to set up Aim. If you happen to try to ride out a bad situation by spreading around Aid Protocol and Hunkering Down for a turn, the Aim is a nice bonus, but overall it tends to be awkward to try to take advantage, and neither of these two classes have any built-in skill synergies like with Deep Cover or Death From Above.

Death From Above
Killing an enemy with the primary weapon that the soldier had height advantage on refunds one action point and doesn't end their turn.

Death From Above is actually much more powerful when rolled as an AWC skill than its natural place on Sharpshooters, as the key factor that prevents Sharpshooters from chaining it is that Sniper Rifles require two action points to fire. This doesn't apply to Rifles, Cannons, or Shotguns, so Specialists, Grenadiers, and Rangers are all able to chain Death From Above for as long as there's targets that'll die in one hit and ammo to burn on killing them. Who needs Serial?

 Rangers in particular have strong incentives to run the light armors that all come with a Grapple, making it easy to pop to high ground in preparation for a Death From Above kill, so it's generally pretty consistently amazing on them without having to really change anything about how you use them. (Unless you normally are very obsessive about Slashing things, I suppose) Even for a heavily melee-oriented build, it's easy to slip in a Death From Above kill before going on to Slash something else.

 For Specialists, Death From Above is a bit more contextual. If you don't have the Alien Hunters DLC, it'll periodically help, but going out of your way to leverage it will be a bit awkward. If you do have the Alien Hunters DLC and like to slap the Icarus Armor on a Specialist anyway, this is a pretty straightforward upgrade that's easy to take advantage of; jetpacking up to high ground is fairly easy, and in a dire scenario your Specialist can always teleport to high ground if there is any nearby. If you prefer your Icarus Armor on someone else... well, consider giving it to your Death From Above Specialist anyway.

 Grenadiers can also get use out of it, and the Icarus Armor point applies to them just as straightforwardly as to Specialists, but they're sufficiently incentivized to use grenades and Heavy Weapons and to soften up enemies that it's a little bit less appealing than for Rangers and Specialists. With how they're fairly ammo-hungry, it can also be a pain to even squeeze in opportunistic Death From Above kills, and their poor accuracy makes them bad at killing things. It's not remotely a dud ability, but it's not an ideal roll.

 Do keep in mind that Stock-derived kills will still trigger Death From Above, though. If you do roll it on a Grenadier, their poor Aim can be worked around by having them pick off near-death targets via their Stock. By a similar token, a Ranger with a Stock on their Shotgun can potentially 100% reliably slip in a kill-shot on even a far-away target in High Cover if the Stock is good enough to finish them off.

Deadeye
Fires a shot with the primary weapon which does 50% more damage if it hits, but reduces the final accuracy value by 25%. 2 turn cooldown.

Frustratingly, Deadeye requires two action points to make use of even when used by a non-Sharpshooter.

Deadeye can be pretty amazing on a Ranger, as Shotguns have sufficient Aim climb in-close to make for a much more reliable shot than a Sniper can ever hope to achieve. In conjunction with Rangers having innate skills encouraging chasing kill-shots in particular, it's a pretty decent thing to roll for them, especially since they can overcome its movement limitation somewhat with Run And Gun.

 For Specialists and Grenadiers, it's a lot more dubious. They can still generally get more accuracy than a Sharpshooter could, but they can't leverage Deadeye particularly well regardless and Grenadiers in particular would generally rather use Chain Shot if they want to go for an erratic damage boost; Chain Shot being multiple shots is a better synergy with Shredder, for one, and for two it's just plain better damage if both shots connect, with an easier Aim penalty to manage.

 And yes, there's a lot of AWC skills that are pretty cool to roll on a Ranger and a bit of a dud otherwise.

Kill Zone
Designates a cone-shaped region, in which the soldier will automatically perform Overwatch fire on any enemy that passes through or fires from within the region, lasting until the soldier's primary weapon runs out of ammo or their next turn arrives. 3 turn cooldown.

Note that this always works at Squadsight ranges, even though by definition if it's an AWC skill the user lacks Long Watch and Squadsight.

 Anyway, Kill Zone is overall a lot better on non-Sharpshooters than on Sharpshooters. Not quite so dramatically as with Death From Above, but the fact that other classes get Aim climb for close-up targets instead of always suffering Aim penalties makes it a lot more reliable, and eg Grenadiers can use it to spray Holo Targeting+Shred on enemies. Unfortunately, just like Deadeye it requires two action points to activate, and so you cannot move and Kill Zone in the same turn unless Run And Gun gets involved. This sharply limits its utility.

 For a Specialist, it can be genuinely worth considering using Kill Zone on already-active enemies thanks to Cool Under Pressure. You'll still be operating at an Aim penalty, but less than other classes, and you'll still be able to crit, which can be particularly relevant against Stun Lancers since they very consistently charge your lines. In a bad situation, Kill Zone from a Specialist might save the day.

 For Rangers, Kill Zone can be surprisingly powerful, particularly if circumstances contrive such that your Ranger is basically right on top of a pod while your squad is still Concealed. (ie you move the Ranger up, and then the pod gets even closer without actually flanking anyone) Getting multiple close-range full-accuracy blasts off on targets considered to be in the open can be stupendously lethal from a Ranger, as Hunter's Instincts will in fact apply in that case. Just keep in mind that Shotguns suffer severe Aim penalties from distance; you shouldn't be trying to use Kill Zone to catch pods entering the edge of your Ranger's vision, where that's an okay option for Grenadiers and Specialists (Or a Ranger carrying a Rifle) if you have a high degree of confidence that a pod is going to come from a specific direction. (Maybe you have a Phantom/Conceal-capable Ranger scouting, and the terrain makes a visible pod's patrol path more predictable)

 As an aside, I'd rate Kill Zone as a supremely poor roll for non-Specialists, except the thing is Saturation Fire is actually not in the AWC list. So even though it's overall better than Kill Zone, even for Overwatch ambushes, the point is moot.

Serial
Activated ability that causes kill shots with the soldier's primary weapon to cost no actions for the rest of the turn. 4 turn cooldown.

This is actually potentially more powerful on a non-Sharpshooter if you can set up a kill chain successfully, since other classes can kill until their ammo runs out, reload, and keep on going uninterrupted without any external support necessary. I tend to be more impressed by Death From Above, but Serial isn't remotely bad, and in particular can be used in situations where Death From Above isn't available as an option. (eg flat maps lacking high ground, or at least lacking safe high ground)

 Specialists get the least use out of it just from having the weakest weapon, and it can be particularly inconvenient to have a Specialist roll Serial if you've been having them carry the Bolt Caster, but having it available is certainly never bad. Even an offensive Specialist can always Serial away a couple of enemies and then Hack or Combat Protocol or whatever it is you wanted them to do in the first place. Just make sure to preferentially load up their Rifle with Weapon Attachments that fit well to Serial, like Expanded Magazine or a Scope, rather than stuff like Repeaters or to a lesser extent Stocks. (Though to be clear Serial does count Stock-derived kills, so a Stock can actually be useful for ensuring you get a Serial kill on a badly weakened enemy)

 On Grenadiers it's a little un-synergistic with their general role of softening enemies up for their squadmates, but for one thing it synergizes with Salvo: launch a grenade or a Heavy Weapon, and then use Serial to mop up the remains. And, again, having it available is never a bad thing. Just remember that Serial won't trigger off of eg kills landed with a Heavy Weapon or grenade.

 Rangers are naturally good at flanking multiple targets and have extraordinary damage in that circumstance, so they can be quite effective at tearing apart groups of lower-tier enemies, particularly on lower difficulties. It's arguably a little redundant with Reaper, but having both as options isn't remotely bad, especially in big missions where you might want kill-streaks close together.. The final mission in particular actually has not only a lot of enemies in general but is guaranteed to have extra-large pods of enemies where this kind of kill chain can be incredibly useful, instead of just a cute hypothetical.

It's slightly less amazing for Rangers than one might expect because, strangely enough, Serial cannot be activated alongside Reaper or Run And Gun. If you activate Serial, you'll be blocked from activating them, and conversely if you activate Reaper or Run And Gun you'll be forbidden from activating Serial. No freely swapping between Slashes and shots as you get flanks, and no kicking off a Serial streak with a Run And Gun Dash to a flank. This isn't a big deal if you know about it, but can be deeply unpleasant if you build a plan around Serial combining with one or the other and surprise! Turns out your plan is impossible!
Minor mechanical niggle: Serial cannot be activated unless the user currently has 2 action points. This can be incredibly frustrating if you, for example, moved everyone one action point worth of distance, saving your Serial-as-bonus-skill soldier for last, and whoops their movement activated a pod... but while it's dumb that it demands you currently have 2 action points, outside of edge cases like that it's not a real limiter if you keep it in mind. Just remember to activate it before moving (Or otherwise spending an action point), simple as that.

Phantom
This soldier starts every mission in Concealment, and the rest of the squad being revealed does not break this soldier's Concealment.

Yay?

 In the extraordinarily unlikely event that you get something like 4-5 different soldiers acquiring Phantom through the Advanced Warfare Center, this can create a situation where you can go into no-Concealment missions with full Concealment while having class variety. That's more of a neat gimmick than anything else though, and outside of that... there isn't really a class that actually appreciates Phantom in a unique way compared to a Ranger.

 In fact, it can easily be a disadvantage, taking away the ability to set up a full Overwatch ambush the way you're used to. And no, you can't use retraining to get rid of Phantom; get to training a new Grenadier or Sharpshooter if you want Phantom to stop getting in the way. This isn't even getting into the issues with remembering who has 'lucked' into Phantom; sure, you might be able to adjust your Overwatch ambush tactics to make Phantom not a problem, but only if you don't forget that your secondary Grenadier has it and so needs to be the one launching the initial grenade.

 It's particularly egregious for a Kill Zone Sharpshooter, where it makes it impossible for you to perform that initial Kill Zone-backed Overwatch ambush, period. Sorry, retrain that Sharpshooter into a completely different build, or give up on them entirely!

 Phantom is the one skill I wish was just flat-out not in the Advanced Warfare Center's pool. Especially infuriating is that Conceal isn't, even though it would sidestep the problems Phantom has. It would still be a lackluster thing to roll, but it wouldn't be actively harmful the way Phantom is.

 On the plus side, it is barred from Specialists to avoid conflict with Gremlin skills. So you don't have to worry about them missing out on triggering Guardian on an Overwatch ambush, which while not as painful as Kill Zone being neutered would still be pretty frustrating.

Shadowstep
Reaction fire does not activate against this soldier.

Rangers are by far the best, most consistent user of Shadowstep, but it's not like it's actually bad to have it on one of your other classes. It may never actually benefit you in an entire run, but on the other hand it may be what saves your best soldier's life in a bad situation. The only time it can be an actual negative is when you find yourself in a situation where you want the Shadowstep soldier to draw fire for someone else -and usually the fact that they have Shadowstep will make it easier for them to get into a position to hurt the Overwatchers, handling the problem that way.

Grenadiers can put Shadowstep to okay use at times as well, particularly if you're running them less focused on explosives (Primarily: you skipped Salvo) and so flanking is something that makes sense to pursue and so movement makes sense to pursue. It won't crop up very often for reasons I'll be getting into a bit later, but still, it's okay to roll.

Run And Gun
Immediately provides an additional action point, which cannot be spent on movement. 3 turn cooldown.

Run And Gun is consistently excellent on all three class that can roll it as an AWC skill.

 Sharpshooters are the most obvious beneficiary, being able to actually move to a new position and then snipe. This can be the difference between leaving your Sharpshooter behind for a timed mission vs bringing them along, and in general makes sniping Sharpshooters vastly more viable since they can get flanks, move to high ground, re-position when flanked, and otherwise maneuver without having to sacrifice their Sniper Rifle shot. Gunslinger builds are, of course, also able to put Run And Gun to good use, but it's a bit less dramatic, and if you have a Gunslinger-focused Sharpshooter roll Run And Gun you might want to reskill them into a sniping build since that's normally so under-strength, if you're interested in actually having fun with a Sniper Rifle-focused build. Alternatively you can enjoy the ability to Run And Gun for two Quickdraw Pistol shots followed by Faceoff or Fan Fire. Either way.

 Specialists can also put Run And Gun to a surprising amount of use, particularly medically-oriented Specialists who can end up wanting to eg Aid Protocol and Medical Protocol and still take a shot. Being able to drop an Aid Protocol and then move to flank and shoot is also very useful, and of course a Dash that turns into a flanking shot is useful regardless of exact build. Run And Gun is also very synergistic with using the Bolt Caster on a Specialist, allowing them to reload and fire while still moving or dropping an Aid Protocol or the like. In general, Specialists have enough action economy pressure that Run And Gun is fantastic to roll on one.

 Grenadiers can put Run And Gun to plenty of use as well. Salvo can allow for a faintly ridiculous alpha strike of two grenades or a grenade and a Heavy Weapon followed by a regular shot, or heck two grenades and a Heavy Weapon shot. If you've taken Heavy Ordnance, it can even be three grenades in one turn! This can make ambushing from Concealment 3 pods actually practical, all by itself. As Salvo tends to encourage having your Grenadiers fall behind, the potential to use Run And Gun to let them catch up while still doing something useful is also noteworthy. Support-with-Cannon builds tend to get less use out of Run And Gun, but there's still the ability to Dash for a flanking shot, which is always useful to have at your fingertips.

 Rolling Run And Gun is always good.

Implacable
Once per turn, landing a kill during your turn provides a single action point. This action point can only be spent on movement.

Sniper-oriented Sharpshooters particularly appreciate Implacable, since it lets them semi-consistently move to keep up with the squad without having to sacrifice Sniper Rifle shots. Even more so than Run And Gun, this can make a sniping Sharpshooter justifiable to drag into one of the harder timed missions. Pistol-oriented Sharpshooters can still get plenty of use out of it, of course, but it's not quite so dramatic an improvement. Keep in mind that Implacable's bonus movement is automatically used up first if a soldier has non-Implacable actions, such as due to Serial or a Hair Trigger activating, and moves; this can allow you to land a kill and then promptly move to high ground or a flank or whatever before firing another shot. This applies to any class, but it's especially important to not waste it on a Sharpshooter, particularly one with Death From Above.

 Specialists aren't as bad as Sharpshooters about struggling to keep up with the squad while doing their thing, but the issue is sufficiently there that Implacable is still nifty to roll. Run And Gun is usually better for a Specialist, but Implacable is by no means bad.

 It's probably least useful to Grenadiers, who are heavily encouraged to use their Grenade Launcher to soften up enemies or one of their shooting-but-not-killing abilities to contribute to a fight. You'll still occasionally trigger it, and it can help Salvo Grenadiers in particular keep up with the squad, but it's a somewhat forgettable bonus on properly-used Grenadiers.

Untouchable
If the soldier lands a kill, during the next enemy turn the first time the soldier should have taken damage from enemy action they won't, even if it's an action that is normally incapable of missing such as a grenade.

Untouchable isn't quite as amazing on non-Rangers as on Rangers, but complete immunity to the next attack is excellent regardless of class.

 While Sniper Rifle-focused Sharpshooters don't get a lot of use out of it, Pistol-oriented Sharpshooters are excellent abusers of it. They can even do things like land a kill with Lightning Hands and then dash out in the open to draw fire from other soldiers, if you've reduced the enemy down to one unit but can't actually finish it off just yet. As such, if you have a Sharpshooter roll Untouchable who you'd otherwise been tooling as Sniper Rifle-focused, you might want to retrain them into a Gunslinger.

 Grenadiers are generally fairly support-oriented, but Untouchable will periodically help out regardless, and if you want to you can retool a Grenadier that rolls Untouchable into more of a kill-oriented piece. I tend to run two Grenadiers, personally, and at that point it's fairly easy to support having one as a support piece and the other as more of a kill-y piece. They don't have a ton of options for pushing in that direction, but if nothing else you can retrain them to take Chain Shot, Hail of Bullets, and not-a-great-example-but-I-guess also Rupture.

 Specialists tend to get the least use out of Untouchable, but even if you're not specifically trying to take advantage it's liable to crop up eventually. If you have the Alien Hunters DLC, consider having a Specialist who rolls Untouchable take the Bolt Caster if you don't normally do so; its exceptional damage and inability to Graze makes it very prone to securing kills, making it vastly more likely your Specialist will get to leverage Untouchable.

Rapid Fire
Fires two shots with the soldier's primary weapon, both of which occur at -15 to Aim.

As with Chain Shot and so on, Rapid Fire can't be used by Sharpshooters at Squadsight ranges. That right there makes it fairly lackluster when rolled on a Sharpshooter. Better than Chain Shot, but still pretty situational. Unintuitively, it tends to be better on Pistol-focused Sharpshooters, as they're more likely to already be in range to Rapid Fire than one you're trying to have Squadsight things to death. Regardless, note that it doesn't trigger Death From Above on a kill -which of course also makes Death From Above a little less useful to a Ranger who rolls that.

 For a Grenadier, Rapid Fire is a straightforward replacement for Chain Shot, and in fact you should ideally reskill any Grenadier who rolls Rapid Fire after already taking Chain Shot because there's literally no reason to use Chain Shot once you have Rapid Fire: Rapid Fire doesn't have a cooldown and can still fire a second shot if the first one misses.

 For a Specialist, Rapid Fire isn't a particularly natural fit to their role, but having the option to spit out massive damage all of a sudden is never bad. Too bad they don't really have any native skills to synergize with it. Oh well.

 Deep Cover
If the soldier did not attack in a turn, they automatically Hunker Down when their team's turn ends.

Just as a Ranger can appreciate Aim, a Sharpshooter can appreciate Deep Cover, and in fact a Sharpshooter probably appreciates it more since it helps push back against the limitations of a Sniper Rifle: you need to reload, and so can't fire your Sniper Rife? That's okay, you can still advance to a new location while being heavily protected and setting up a boost to Aim on your next shot. (You did take Aim on your Deep Cover Sharpshooter, right?) Run And Gun is usually more useful, but Deep Cover isn't remotely bad.

 On Grenadiers, Deep Cover is... existent. I haven't bothered to test how it interacts with not-technically-attacking abilities like Suppression and Demolition, so I don't know if using them will bar it from activation, but generally speaking a Grenadier shouldn't be having Deep Cover activate.

 Just like Ever Vigilant is barred from Rangers, Deep Cover is barred from Specialists.

Lightning Reflexes
The first reaction fire performed against this soldier in a given turn automatically misses.

Lightning Reflexes is unique among Advanced Warfare Center abilities in that it's not natively available to any class. It can only be acquired via the Advanced Warfare Center's bonus skill mechanics.

You might be worried it would make Shadowstep useless, but it's actually barred from the Ranger to avoid precisely that issue.

 For those classes that can get it, it's... occasionally nice? Honestly, it would be much more appreciated on a Ranger, since they tend to want to be on the move regardless of their exact build. For non-Salvo Grenadiers it's not so bad, since they generally have no reason to not move and then shoot, but that's about it.

 More generally, Lightning Reflexes is held back by two points: firstly, enemies using Overwatch is very rare. Heavy Mecs are the only enemy that routinely enters Overwatch, and generally only on initial activation. The other big issue is that Overwatch can be terminated simply by doing damage to an enemy. It's fairly rare for you to be in a situation where you desperately need to move and can't simply dish out damage to the Overwatcher beforehand. Even in an extreme scenario like your entire squad having been caught by a Psi Bomb... if any of them is a Sharpshooter with Quickdraw or Lightning Hands, you can take a shot at the Overwatcher. If any of them is a Grenadier with Salvo, you can lob a grenade or Heavy Weapon. A SPARK can potentially Overdrive, reload, fire, and still have time to move, or lob their Heavy Weapon or Bombard before moving, whatever. A Ranger who's taken Shadowstep can solve the problem with a Slash.

 So Lightning Reflexes existing as an AWC skill is cute as an Easter egg, but in practice that's about it. It's not quite a dud roll, but it's not far off.

 All the above is also why Shadowstep isn't super-great, incidentally.

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 Next time, we return to talking about classes by focusing on the Psi Operative, the last non-DLC class in the base game.