Tactics (Long War)

This covers anecdotal or general concepts and tips that might not fit into any other place, usually just player specific styles or advice that might help you during the tactical combat.

General Advice & Tips for the Tactical Layer

Know Yourself

A good Commander knows their soldiers well. Particularly with Training Roulette on, keep an eye out for any good ability combinations, and make note of who has them. For example, someone with high move and Packmaster (+1 use to all items) would be good to give an Arc Thrower. Or soldiers that get Low Profile should be marked for Psionic Training. Opportunists with any multi-overwatch shot abilities would be good for Chryssalid and Zombie infested missions, and so on.

Know the Enemy

Study the alien database well: the expanded abilities displayed by the aliens can catch even a veteran vanilla player unaware, such as Berserkers being able to jump from the get-go, or Thin Men squad leaders getting Squadsight.

Medics: they aren't useless

A Medic is one of the most useful classes to have around, they can keep your soldiers healthy during battle and they increase the survivability of friendly (and enemy) soldiers with their Smoke Grenades. They may lack the killing power of the other classes, but when you get poisoned by a Thin Man or strangled by a Seeker, you'll be glad that you have them with you. They now also have an ability called Field Surgeon that has a 75% chance (100% if you field 2 Medics with it) of reducing non-critically wounded injury recovery time. Make one a Lieutenant with Stay Frosty, and you have a nice buffer for the expanded recovery mechanics of Long War.

Divide and Conquer

Usually it is never a good idea to split your team into two, but on urban maps, there is some merit in doing this. When you have both your squad upgrades, you can split your squad into fire teams of four people. This is useful because it lets you breach buildings and other structures much more efficiently and sets you up for more flanking maneuvers. It also lets you get out of deadlock situations where you are in a prolonged fire fight with alien opposition, without any opportunity to move forward.

Meld

It is not worth potentially losing valuable soldiers to recover Meld. If it's in a good place to grab, then go for it by all means. If not, don't waste a soldiers well-being on it. Also, the better you are doing, the less Meld you receive, so don't worry about missing it. Meld becomes increasingly necessary in the late game. In addition to Meld canisters, Meld is gained at an automatic rate of 0.4 alien corpse brought home from a mission (rounded down). Mechtoid and Floater/Heavy Floater corpses also provide higher fractional Meld amounts.
Rushing the Meld canisters can be risky, one strategy is to get in sight of the Meld canister and then wait and see what kind of sound it's making. Meld canisters only expire the turn after they are chirping at a frequency faster than 1/sec (once per second). More precisely, it will chirp at a rate of about 6 times every 5 seconds, or 1.2/sec. Listening to the canisters can thus help you gauge how aggressively you need to act. Put the camera to 'terrain gliding' with F9, and look around when starting a mission: you may catch the movement of the canister's 'turret' if you look for a bit (Note: this is only possible with 'Recon' option enabled in Second Wave). On 'top' of UFOs is a common place (and are easy to spot in this method), so if you do not have a way to access them, consider them a write-off and take your time, unless you think you can rush to complete the mission before it goes off.

Use side of map

Don't make your soldier go to center of map for flank or you will get additional enemies from every direction. Use side of map if you want a great flank. The probability of meeting new enemies is almost 1/2 ~ 1/3 if you use edge of map rather than center of map.

Equipment

Chem Grenade

An extremely useful type of grenade, try it over Flash-bangs and Psi-grenades. Although it doesn't affect the ever annoying Chryssalids and Thin Men, it can be used against all other enemy types. Reduces aim, movement points and damages upon actions. Also extremely useful later against Cyberdiscs, Mechtoids and Sectopods with insane hit-points and damage reduction. Can effectively reduce damage reduction of Hardened enemies to 1-3 from (late stage) 8-10, making them much easier to kill.

Arc Thrower

An easy method to capture aliens is to have a unit with Packmaster/Repair carry an Arc Thrower and a unit with Psi Panic. Leave one enemy last such as Muton/Floater/Outsider (or any other low-will enemy), use Psi Panic on it and make liberal use of the Arc Thrower until successful.

When an alien is affected by acid and only has a single hit point left, he will always refuse to use an action that would otherwise cause it to be triggered and kill him. This can be used to your advantage to prepare unwary invaders for multiple, safe stunning attempts with an Arc Thrower. If an enemy unit is shredded, acid will cause 2 points of damage. Enemies that are shredded, acided, and have 2 hit points left will NOT move, or they would die. Be careful when psi-panicking acid affected enemies with 1 HP left, they will often panic move, killing themselves (thus no Arc Thrower capturing).

A good, albeit dangerous, way to earn more scientists and money is by giving captured aliens to Council nations. As such, you should always try to capture at least one alien, when doing a mission. Downed Scouts and Fighters are excellent ways to do this. You can have a near infinite number of captured aliens at your base and countries will usually only ask for one specimen per request. In addition, you can sell most of the alien weapons you'll get on the Gray Market. As you will neither be able to use them yourself, nor get Council requests for them, until much later (when you complete the research for them): there's no harm in selling a portion of this stock for most of the campaign.

SHIVs

Liberally use SHIVs, they are much better than the standard rookie, can take more damage and can create moving cover. They might not get any experience and be less effective than a regular soldier, but they can be outfitted to oblivion due to the much expanded SHIV tree present in Long War. A SHIV does not suffer from fatigue or panic. If you want to try and take all the missions that the game throws at you, having some SHIVs is a good idea.

MECs

The MEC Grenade Launcher and Proximity Mine Launcher can be fired while the MEC is acting as a heavy cover element with One for All without breaking the ability. Restorative Mist will not stabilize a critically wounded soldier. Proximity Mines can be automatically detonated by any other explosive going off with the mine inside the explosive radius. The Kinetic Strike Module can be used to punch through any destructible environment elements; use it to make artificial holes in UFOs. The KSM does not work with In the Zone, but the KSM and Electro Pulse do get damage increases with HEAT Ammo (important for Goliaths). MECs cannot be strangled and possess partial immunity to acid.

Battle Scanners

Battle Scanners become a requirement when Seekers start coming into the enemy squad rotation as they can seriously wreck any well laid plan. Seekers have had many shackles taken off their AI, so 4 Seekers can decloak and strangle you in one turn unless you do something about it. If you have Training Roulette on, any soldier class has a chance to get Scanners as a perk (and will carry two per mission). And later, if/when you can afford the Meld, give a few mid-line soldiers Bioelectric Skin, have each one take a turn on missions, and regroup when facing a Seeker pod (hopefully, there will be no grenade-wielding aliens around). Either way can save up an item slot for whatever else you think might help.

Grenades

You might have a juicy HE Grenade target hiding behind a wall. You have the perfect throw, but think before you throw. You might remove his cover, but you might also add line of sight to the three other aliens that were on the other side of the wall, now you have to contend with more enemies and you might be caught in a very bad position. As such, generally throw the grenade as the first thing, not the last.

Mimic Beacon

Placing a Mimic Beacon and a Chem Grenade on each other acts like something between a poor man's Shredder Rocket and a Flashbang: most aliens will swarm around the Beacon, the acid cutting into their DR, and dinging the HP of organic enemies while reducing their aim and movement. Keep in mind that some aliens will still fire, even if out in the open in this situation, so for extra safety, get you soldiers out of line of sight in that round, and next round you'll know that most of them are conveniently clustered around the beacon for your AoE attacks! Be cautious of any on overwatch when you move back into line of sight.

End Game Armor

Don't just go with the heavy Titan Armor as always. Archangel Armor is one of the best armors available, and not just for that Squadsight Sniper. You can easily trade hp for the increased mobility and defense bonuses, plus the flying ability and the associated aim bonuses. Your units will rarely miss shots and will not be in danger of getting flanked. You can also laugh at those charging Chryssalids and Berserkers. If flight doesn't interest you, the Vortex Armor for your psionic troopers gives the same HP bonus, but slightly more mobility and defense, plus the +20 boost to will, and eliminates fatigue. Certainly, it's an expensive investment, but it (or the lesser Aurora Armor) the only way you may be able to get to use the devastating Rift attack in battle.

Game Mechanics

Rocket Scatter

The number of tiles that shows up as a rocket's scatter means that the rocket has a 68% chance of hitting somewhere within that many tiles from the center of the shown blast zone. The 68% is derived from the statistical normal distribution where 68% is the number of all values that fall within one standard-deviation of the mean. By applying this, a rocket of scatter 1.5 tiles will land within 1.5 tiles of the center of the blast zone 68% of the time. By doubling the rocket scatter you are given, you arrive at two standard deviations from the mean (average). This means that there is a 95% chance that a rocket will land within 2x the shown rocket scatter from the center of the blast zone (i.e. a rocket of scatter 2.0 tiles will land within 4.0 tiles of the center of the blast zone 95% of the time). Rockets do not scatter vertically.

Chatter on the Wind

Every two turns your soldiers will hear the enemy movement beyond your line of sight. The directional indicator you are shown points to the CLOSEST enemies to your soldiers. The only aliens that make no audible sound during this reveal are Outsiders, though they will still trigger the indicator's mechanics (as usually they'll be the last aliens in a UFO assault mission). And learn the sounds the various enemies make during alien activity to get a feel of enemy composition: Sectoids chitter, Thin Men rasp, Mutons roar (Berserkers & Elites have slightly different sounds), Floaters rocket and growl, Cyberdiscs make ufo-y sounds, Drones hover-whine, Mechtoids and Sectopods share heavy footfalls, you hear the Chryssalids in your nightmares, the Ethereals 'talk' and EXALT make scrambled radio chatter. In landed UFOs, a sharp ear (and a good sound system) can tell you if the roaming pods are in the UFO (the clanking of boots on alloy floors) or outside (the more muffled padding of aliens on soil) - at least for the bipedal aliens. The length of Alien Activity will also give you an idea of how many aliens (and EXALT agents) there are left. On Council and Covert Op missions, if the alien turn barely lasts a moment, there are no enemies in play, so continue with the mission without worry (until the next airdrop triggers, anyways).

Supression, Flashbangs, Overwatch

Overwatch shots will not crit unless the soldier/alien has the Opportunist perk. Using the grapple hook available on various armors will not trigger overwatch shots, and it appears to not activate pods that can only be seen in transit (i.e. if you can see them at the grapple destination, they still activate). Suppression and Flashbangs will cancel overwatch (although the eye indicator will stay up on suppression). The suppressor taking any damage, target cloaking, and Flashbangs will cancel suppression.

Block the exit!

A soldier can effectively 'lock' a doorway if placed on the tile immediately on one side of it. This is because aliens cannot open doors, they can only charge through them. Similarly, ladders and pipes can be 'locked' by standing at the top of them; Chryssalids, Thin Men, Berserkers, and Outsiders can simply vault up onto any rooftop, however.

Cover

Always keep your units in high cover, for that 45 defense and damage reduction. If in low cover, hunker. Hunkering in low cover is BETTER than standing in high cover. 45 defense with 1 damage reduction vs 60 defense with 1.33.

LOS

Alien line of sight can sometimes be determined: moving into a flanked position will show the shield as red. Moving away from the alien, the point where the shields switch from red to normal marks the limit of the aliens sight. Line of sight range is 17 tiles in a straight line.

When do I keep corpses and other alien artifacts from alien bodies?

As Dr. Vahlen aggressively points out, killing an alien with an explosive will not yield any Weapon Fragments upon death, but what about the other things like corpses?
Follow this guide:
1. Any alien that is hurt by an explosive weapon at any time, will not give any Meld (different aliens drop different fractional amounts of Meld). However, they will give everything else upon death unless any of the following items in this list supersede.
2. Any alien this is dealt the killing blow with an explosive, will lose everything. You will not get Meld, Alloys, Weapon Fragments, or corpses.
3. Any legitimate (i.e. not killed by explosives) alien corpses/wrecks laying on the ground will NOT be destroyed if an explosive weapon detonates nearby.
4. Any unconscious alien captures WILL be killed if they get caught in an explosive blast.

On a related note: blowing up walls of downed/landed UFOs does not affect any of the resource outcome of that mission. However, blowing up intact Alien Computers, Power Sources, etc, will destroy that item.

Alien AI tendency to shoot

1. If the alien's chance to hit a soldier is high, the chance to shoot them is very very high (flanked soldiers, SHIV, MEC).
2. If a soldier's current HP is low enough to be killed in one shot, chance of shooting them increased.
3. If a soldier is using suppression burst, the chance to shoot them is increased significantly.
4. If the alien's chance to hit a soldier is higher than others, the chance to shoot them is increased (you can use Reinforced Armor for tanking purpose because Reinforced Armor lowers defense).

Perk Mechanics

Rapid Reaction vs Sentinel

Rapid Reaction allows for up to 3 consecutive overwatch shots: if the first or second shot misses, your soldier will not be able to take the remaining shots. Sentinel allows for two overwatch shots, the second of which will be taken regardless if the first hits or not. Either one benefits greatly from Opportunist.

Flush

If you Flush an enemy while flusher is at side of enemy, the enemy set the cover position only toward flusher, and that position is easy to be flanked by the other soldiers. The alien who is flushed doesn't consider the other soldiers at all. You don't have to flank him actually when you flush him doing this.

The 50% damage reduction from the perk Flush is applied BEFORE the HEAT Ammo perk. This means that the bonus damage against robotic targets is not reduced by 50%.

Suppression

Successful hit on suppressor negates suppression, so aliens tend to shoot the suppressor first. The suppressor can be used as tank. It's good to make your suppressor have full HP and high cover before using Suppression.

Free Shots

Many perks offer free shots or additional shots, to see which perks allow certain types of free shots, refer to the following list.

1. Light Em Up, Close Encounters and Hit & Run only activate from basic fire (primary & sidearm).
2. In the Zone activates from basic fire, Disabling Shot, Flush, Precision Shot and Rapid Shot, but only from primary weapon shots.
3. Ready for Anything and Double Tap activate from basic fire, Disabling Shot, Flush, and Precision Shot (primary & sidearm).
4. When activated, Double Tap allows basic fire, Disabling Shot and Precision Shot (primary & sidearm).
5. When activated, Run & Gun allows basic fire, Flush, Rapid Fire, Suppression and overwatch (primary & sidearm).

Sorted by ability:
1. Basic fire: activates Light Em Up, Close Encounters, Hit & Run, In the Zone, Ready for Anything, Double Tap. Available from both Double Tap and Run & Gun.
2. Disabling Shot and Precision Shot: activates In the Zone, Ready for Anything, Double Tap. Available from Double Tap, but not from Run & Gun.
3. Flush: activates In the Zone, Ready for Anything, Double Tap. Available from Run & Gun, but not from Double Tap.
4. Rapid Fire: activates In the Zone (on either 1st or 2nd shot). Available from Run & Gun, but not Double Tap.
5. Suppression and overwatch: available from Run & Gun, but not from Double Tap.
6. Steady Weapon: not available from either Run & Gun or Double Tap.

Aliens

Aliens don't like being flanked

When an alien is flanked, they are extremely likely to move to get out of the flank - even if this means moving through overwatch and suppression. If you want an enemy to stay put for next turn, it might not be the best idea to flank him this turn. One exception to a flanked alien running is if there is only 1 XCOM soldier flanking the alien AND that alien has a killing flank shot on that 1 soldier. The moral of that story is, don't put one of your soldiers into a flank just to get a flank on an alien.

Drones

Drones cannot overwatch, nor can they go through closed doors (except in seemingly extraordinary cases).

Cyberdiscs

Cyberdiscs are nearly immune to critical hits in their folded up form, but not in their attack form. If they go on overwatch upon reveal, it can be a good idea to take a shot taking advantage of the crit bonus. Upon the disk folding up, you can then run a scout to pull the overwatch fire thus tricking the Cyberdisc into unfolding again so you can take more shots at it. Using this method can maximize your crit damage potential.

Outsiders

Outsiders are extremely dangerous: they have Muscle Fiber Density, great aim, and health regeneration, but they carry no grenades. Beware on landed/crashed UFO missions, triggering the Outsider pod has a tendency to make other alien pods converge on your position.

Seekers

Seekers can only strangle from a decloak by being landed (i.e. no flying defense bonus) on an open tile in one of the 4 main directions of tiles (no diagonals). They seem to preferentially seek out soldiers that are separated from your crew (Snipers usually), Assaults, and Gunners. Seekers ALWAYS know where every member of your team is, they cheat. A decloaking Seeker, whether they are attacking or whether you threw a Battle Scanner, will trigger Close Combat Specialist. Thus, one way to deal with Seekers is to surround an Assault with other members of your team so that the Seekers can't strangle the Assault; when they try to strangle anyone else, the Assault trips Close Combat Specialist on every Seeker that attacks and hopefully kills all of them. The only soldier who will not react to a decloak, is the soldier who is about to be strangled by the decloaking Seeker.

Ethereals and Rift

Ethereals cannot overwatch. Psi Lance is actually the regular attack of the Ethereal, and deals damage proportional to will (thus very high damage). Things that reduce the damage of Psi Lance and Rift:
1. Every form of DR including cover.
2. Every 10 points of soldier's will reduce damage by 1.
3. Combat Drugs reduce it by 2.
4. Psi Inspiration reduce it by 3.
5. Mind Merge reduces it by a currently unknown scaling amount.

Two suppressions can easily reduce the aim close to zero, while also reducing the range of Rift. Clustered units can be easily wiped out with Rift. The Ethereal will not use Rift if it will get caught up in it as well. Take note that flying units cannot be damaged by Rift. Shredding an Ethereal first is an ideal way to quickly take it down in one turn with enough firepower. While mind controlling an Ethereal will grant Rift, in the final mission the Volunteer will get Rift anyway.

Missions

Knowing is half the battle!

In Long War, you will be given a short description of what type of terrain you will be fighting on. This is very useful information as it lets you customize squads that are tailor-made for fights on that specific type of map. This feature is a godsend, with the increase in classes and their more specialized nature.

Terror Missions

The most dangerous part of Terror mission are the roaming Chryssalids. Chryssalids will frequently charge you in a bunched up group, which makes them excellent targets for grenades and/or rockets. You might not get any carcasses, but that is a small price to pay. This is one of the few occasions where AP Grenades really shine. A MEC with a Flamethrower is the mother of all Chryssalid fears, consider moving MECs near the end of your turn if you know Chryssalids are on the map.

Exalt Missions

1. Consider using Engineers as Operatives for extra grenade spamming. As the Operative cannot carry a main weapon, it is one of the few classes not hindered by this mechanic, as their main damage source (grenades) can still be equipped. Assaults may also be useful for dashing hacks (use Run & Gun).
2. Exalt is a much greater threat with more gene mods and vastly more agents: if you feel you'll need your heavy hitters, pick your lineup and let them stay home when you send your Operative out, so they'll be fresh when it's time for the extraction.
3. You can hack relays to disable Exalt weapons until they reload. Try and keep your Operative in range to hack one in case you get overrun. Note however that this may backfire, as Exalt may end up using rockets and grenades in their turn.
4) It is usually easier to guard the Transmitter rather than the Encoder. If Exalt spawn near the Encoder and rush it from the beginning, don't risk your troops to rush it too. Just converge at the Transmitter for a last stand.
5. Blow up all cover at the Encoder or Transmitter. Exalt agents are dumb enough to rush into that area and stay in the open. Those devices can usually survive one explosion, but save beforehand, just in case. TK Strike is perfectly safe. But in either case, keep in mind if the device is next to an explosive vehicle to avoid catching in in your initial blast.
6. If you can hold EXALT off from both the Encoder and Transmitter, there's an extra Credit bonus.
7. As there is always a larger number of EXALT agents, it's easy to get a few buckets of Meld from the corpses: enough to make it worthwhile to farm these missions while you can still beat it.
8. On Exalt missions where you need to hack 2 relays, Exalt reinforcements spawn when the Operative is in position to do so (a.k.a when they move right next to it), and not when they actually hacks it. You may find it easier by not hacking the relay on that turn and wait for the reinforcements to spawn. As they will usually enter overwatch, you can proceed to hack the relay on the next turn, effectively disabling their overwatch fire, as well as their weapons until reload. They are much easier to deal with this way.
9. On these, it is not necessary to eliminate all Exalt agents - a tall order anyways, given you're only allowed 4 soldiers: feel free to just 'smash & grab,' if the map allows it. Consider sending soldiers with high move, dashing from relay to relay, and haul your ass out of there.
10. There are fewer EXALT squads seeded onto the map when you begin the mission, so the bigger danger is the airdropped agents, who will often appear in inconvenient places.
11. There will also be EXALT airdrops on your way back to the Skyranger, so plan ahead with soldier positions for that. There'll often be 2 or 3 (dropped every other turn) within 1 move's distance of the extraction zone; these you can camp for a little extra XP, or stun for their laser weapons if they're Elites.
12. If you don't mind a bit of Save Scumming, save before the notice for extraction comes up from the Hologlobe. Then let the notice appear, and see which of the two Extraction types it is.

Site Recon

There's a ton more Chryssalids in the Long War iteration of this mission: naturally, bring many explosives, and bring soldiers that can either hit hard or hit twice. Expect the bugs to try to overrun you right from the get-go, so manage your ammo carefully, so there's always at least half your squad ready to fire or go into overwatch. As cover doesn't matter anyways, place your soldiers in lines so the first Chryssalid (often the pod leader, with Lightning Reflexes) doesn't activate all the overwatches, but as each one is slowed by the reaction shot 'bullet time', the rest of the pack members get attacked in sequence. Beware, however, of never taking cover, as there is often at least one other pod of a different alien type on the map (usually Thin Men). Don't place soldiers near the guardrail of the upper elevation, as many of the packs will come from the docks proper, and it'll do you no good if any are hiding in the shadow of the ledge: having the forward soldier (whom the Chryssalids will most often swarm around) away from the edge will make them all swarm at least on the same level, and in a convenient grouping for grenades, rockets, flamethrowers, and bullets/lasers/plasma. Don't forget to blow up those large fish, lest they hatch more bugs on your way back. If you've managed to get the Alien Grenades (Muton Autopsy) Research/Foundry projects done, Alien and the upgraded AP Grenades are supremely helpful. If you got some to spare when you reach the boat: take out a few of it's walls on the starboard side, so your Squadsight Snipers can perch a ways away and hit the emerging Chryssalids and cover the rest of strike 1's retreat.

Large UFO Assaults

Later in the game, you may find Abductor and Harvester UFO assaults to be surprisingly difficult: due to the actually limited size of these two types of UFOs (and how the maps that include them tend to also be small), you may find yourself being rushed by nearly every pod in the map at once. Pick your strike team and their equipment with this in mind, to either push back against this threat (such as psionic soldiers with Mind Control to scramble their ranks, and HP boost items for high-health soldiers), or pull back defensively (soldiers with high move, and Overwatch-boosting abilites), and perhaps either way, to bring plenty of explosives to deny enemy cover.