Overviews of Aliens (EU2012)

Sectoid

Sectoids are the first enemy you will meet. They are a low HP unit with a weak ranged attack. They are known to be extremely aggressive in numbers and timid / cowardly (i.e. start camping/overwatch) if their number is few. They are capable of some limited psionics in the form of Mind Merge. Killing a unit that is performing Mind Merge will also kill the unit receiving the merge.

• Mind Merge: the merged ally receives +1 hit points, increased accuracy, & increased critical hit chance.

Killing a sectoid will leave behind 2x weapon fragments.

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Sectoid Plasma Pistol	3	0	125	27	200	NA	Small	Unlimited ammo

Thin Man

Thin Men are weak, highly mobile units with an average ranged attack. They use a light plasma rifle, making them more accurate and damaging than Sectoids, but they don't pack as much firepower as other enemies.

• Poison Spit: Causes damage each turn for up to 3 turns to any unit poisoned by the cloud of spit. Being poisoned reduces a unit's accuracy by 20%.
• Thin Men explode into a cloud of poison upon death. Moving into this cloud has the same effect as being poisoned by their spit attack.
• Leap: Allows the Thin Man to jump vertically up onto high ground (e.g., roof tops).
• Note: Units carrying a medikit or titan armor are immune to the Thin Man's poison.
• Trivia: The Thin Man's face is a caricature of Sid Meier, boss of Firaxis. Sid's face has a habit of popping up in his games.

Gray Market description: "The Thin Man cadaver begins to severely decompose within hours after death, giving off an overwhelming stench which may relate to toxins stored within its body."

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Thin Man Plasma Rifle	5	10	125	27	200	NA	Large	Suppression 20%

Floater

A fast and aggressive flying unit with a light plasma rifle. They prefer to use their mobility to outflank your squad, and their high mobility grants them an innate defensive bonus while flying. They can be especially dangerous to Snipers.

• Launch: The Floater can launch to any point on the map (ends its turn).
• Floaters are always considered to have at least Light cover even in the open or when flying, unless in proper cover and Flanked. This bonus does not stack with existing cover bonuses - they only recieve the best cover.

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Floater Plasma Rifle	5	10	125	27	200	NA	Large	Suppression 20%

Heavy Floater

A tougher version of the regular Floater with considerably more hit points than a Floater, and a more powerful variant of the Plasma Rifle. They also carry an Alien Grenade.

• Evasion: Enemies targeting this unit when it is airborn suffer a -20 Aim penalty.
• Launch: Move anywhere on the battlefield in a single turn. Launch cannot be used indoors.
• Bombard: Throw or launch grenades over exceptionally long distances.

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Floater Heavy Plasma Rifle	7	10	125	27	200	27	Large	Suppression 35%

Muton

Mutons are very strong units and carry a respectably powerful Plasma Rifle, though they are susceptible to psionics. They are the aliens' version of XCOM's Heavy/Assault class and will aggressively use tactics such as Flanking, Overwatch or Suppression against your soldiers. Wounding a Muton without killing it can intimidate your soldiers and potentially cause panic.

• Suppression: Can fire a special shot that grants reaction fire at a single target. The target also suffers a -30 Aim penalty.
• Blood Call: Unleash a bestial roar that inspires nearby allies of the same species to greater speed, focus, and resolve for 2 turns. 4 turn cooldown.
• Intimidate: Reacts unpredictably when wounded, provoking panic in enemies.
• Mutons carry Alien Grenades, allowing them to injure multiple troops at once and destroy cover.
• They carry light rifles on first month they appear, and rifles after that month.

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Muton Light Plasma Rifle	5	10	125	27	200	NA	Large	Suppression 20%
Muton Plasma Rifle	7	10	125	27	200	NA	Large	Suppression 20%

Muton Elite

An even tougher version of the regular Muton, armed with a powerful Heavy Plasma. Their powerful weapons and good aim and the fact that they appear in groups means they can severely punish you each turn they're allowed to fire, while their ridiculous innate defense and ability to use cover makes them difficult to beat in a conventional firefight. Their major weakness is to psionic attack.

• Suppression: Can fire a special shot that grants reaction fire at a single target. The target also suffers a -30 Aim penalty.
• Bombard: Throw or launch grenades over exceptionally long distances.
• Enemy Defense: +20%/+30% (normal / classic)

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Muton Heavy Plasma Rifle	9	10	125	27	200	27	Large	Suppression 35%

Berserker

Berserkers are extremely strong and very tough melee units, susceptible to their own bloodlust; they have a habit of chasing after whichever unit damaged them last. Although aggressive in nature, they can exhibit some tactical decision to fall back and regroup with other mutons.

• Bull Rush: Charges through cover and causes damage to any units within a small radius.
• Blood Lust: Allows the Berserker to charge an enemy that wounds it.
• Hardened: Hardened units receive extra protection against critical hits (-60% chance to crit)
• Intimidate: Reacts unpredictably when wounded, provoking panic in enemies

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Muton Blade	10	33	125	2	NA	NA	Small	No reaction shot

Outsider

Outsiders are relatively fragile alien units that are only encountered on UFO missions. They are the early commander type units that will remain in their chamber on the UFO until discovered. Their purpose seems to be to defend that position, as they will not go far beyond it. They will be replaced by sectoid commander after you assault alien base.

• Capturing one is required to progress the main plot.

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Outsider Light Plasma Rifle	5	10	0	27	200	NA	Large	Suppression 30%

Chryssalid

Chryssalids are fast melee units. Their Implant attack is particularly dangerous. Their corpses can be used to make Chitin Vests, an equippable item that makes your soldiers tougher and more resilient to melee damage. Since melee attacks ignore cover, Chryssalids are best fought by abandoning cover completely, falling back into the open, and concentrating your fire. Chryssalids are where the changes in the action system are most notable. While not fundamentally different from their counterpart in the original, so long as you are far enough away to force them to dash they are significantly less dangerous, often running right up to your soldiers and ending their turn there.

• Stun Immune: This unit cannot be stunned with the Arc Thrower; taking a live specimen is not possible.
• Leap: Allows vertical leaps onto elevated surfaces during movement.
• Poisonous Claws: "Poison enemies wounded by a melee attack."
• Implant: "Victims are implanted with a Chryssalid egg if they are killed by the attack. (not from poison caused by Poisonous Claws." - A successful implant converts the victim into a zombie that eventually hatches into another Chryssalid a couple turns later. Killing the zombie prevents this transformation from occurring.
• Hardened: Hardened units receive extra protection against critical hits (-60% crit chance).

Cyberdisc

Cyberdisc - open assault form

Cyberdisc - closed disc form

When a Cyberdisc appears you should prioritise them over other aliens you may be fighting. The disc will likely charge in to your midst and take a flanking shot.

Discs aren't very subtle, and will use their move when you first see them to charge at you. Try to burn them down on the turn you see them, because they are very fast and can often get a flank on their next turn unless you fall back. HEAT ammo Heavies can do heavy damage to Discs and the fact that they tend to fly high means your snipers will probably have a good shot immediately. A closed disc is Hardened, so is very difficult to crit, but otherwise is hit and damaged normally. When the Disc attacks it will open up in order to fire, making them more vulnerable. The cyberdisc will close up again on your turn when hit, so make sure to hit it with something high damage for the first shot to make the most of the opportunity for a a critical.

Also note that they do carry an Alien Grenade, so keep your troop's proximity to one another appropriately in mind.

Drones only repair the Disc they spawned with for 3 HP, so as long as you kill the Disc quickly enough, Drones should be more of an annoyance than a serious problem. The drones usually start close to the Disc, so they can be destroyed by it when it explodes on death. Using a rocket on the group is a good way to take out the drones while also dealing damage to the Disc itself. A skilled commander will be able to take advantage of this, and have the Disc's death damage (if not outright destroy) the drones, and any aliens that happen to be near it.

If all else fails, and you can afford the 3 Damage (and not moving into range of any other aliens), an Assault with a Scatter Laser or Alloy Cannon and Rapid Fire can make short work of them.

Interestingly, they're fairly uncommon in Impossible difficulty: for as soon as Sectopods begin to appear, they will be launched en mass, making Cyberdisc appearances infrequent.

For their Autopsy, a kill NOT using explosives is required. It will give you access to the Tracking Module for your Interceptors, a one-use item that extends the amount of time of an air engagement. Not too necessary, as the only time you may require them is when attempting to take down Battleships or the Overseer UFO, and you have only one ready interceptor on that Continent (but, if you have two or more interceptors on a continent: the subsequent Interceptors can be launched when the previous one is either returning to base, or is destroyed, thus reducing the need of this item).

Drone

Drones are weak flying robotic units with a weak ranged attack. Their purpose is to repair accompanying Cyberdiscs and Sectopods during combat.

• With Foundry Upgrades, the Arc Thrower can be used to 'hack' Drones and seize control of them for the duration of a mission.
• Captured Drones can not repair a friendly SHIV unit. However, they can self-detonate, dealing damage similar to frag grenade.

There isn't much to fighting Drones. They have a pretty small frame so it may be difficult hitting them, though even if you miss they really can not do much in the way of retaliation. While not particularly dangerous, they take considerable time to destroy and can end up causing injury while your squad is preoccupied with bigger threats.

Be advised that they will almost always appear alongside stronger robotic units such as Sectopods. This makes drones easy targets for rockets and grenades. Heavies with HEAT ammo in particular can destroy drones with a single grenade (on classic or below) or shredder rocket/alien grenade (on impossible). This makes it easier for the rest of your squad to focus on the heavier machines.

They will repair their accompanying Cyberdisc/Sectopod for 3 HPs each time, and seem to only ever do so for their Cyberdisc/Sectopod, and not one another, nor any other spawned Cyberdiscs/Sectopods/Drones. Most of the time, they will stay near their Cyberdisc/Sectopod, save for on Terror Missions, where their significant movement will make short work of many civilians in each turn if not quickly taken out (often while you're busy engaging their Disc/Pod). They do tend to make repairing the main unit a higher priority than attacking, though.

Hacking Mechanics & Hacked Tactics

You will need the Foundry, the Drone autopsy completed, and some of their wreckage for the Foundry Project (don't worry, you'll be destroying plenty of them), and, once all that is complete, a soldier equipped with an Arc Thrower. The biggest danger is that Drones will almost always be in the company of Cyberdiscs (which may kill the drones upon their death), or Sectopods (which if you rely on Heavies with rockets and the HEAT ability to destroy, you might destroy the drones in the process).

Unlike with capturing aliens, damaging them first is not required (and is not desirable in this case), and has a 100% success rate. Fortunately for your troopers, the range to hack is several tiles larger than an attempted stun. Once Hacked, you have full control of them for the rest of the mission, and they will effectively be counted as additional troopers (and thus, excellent for Snipers with Squadsight), for as many Drones (and Arc Thrower uses) as there are left. Hacking may be most worthwhile in Impossible difficulty, when their 7 HP may help them survive an attack or two. Getting two or more is ideal, as you can use them to heal one another indefinitely. As they can fly, their best use is as scouts/distractions, flying high above an alien; which if it tries to fire in retaliation, may have a high chance of missing the shot. Their own meager shot attack can still help whittle aliens down, and is useful to assist in corralling Berserkers. Lastly, having 1 or 2 Drones following and supporting/repairing (their repair beam has a very large range) your own S.H.I.V.s makes for a near-indestructable force, and is deliciously ironic.

They can not use cover (though you may still want to stay near it, as cover may still 'intercept' shots.) When the mission ends, they are apparently dismantled for the Weapon Fragments and Alien Alloys, and will not be available for further deployment.

Ethereal

When you face these ancient aliens prepare for a very tough fight. Do not expect SHIVs to be immune to them. Ethereals can use pure psionic force against their foes instead of purely mind centered attacks. These attacks actually do more damage to SHIVs than to regular humans as SHIVs have no Will to defend them.

Ethereals are entirely absent from the game until you assault the Overseer UFO, at which point they will always be found at the helm of a UFO. You will only ever face one Ethereal at a time and they will never wander from their spawn positions until provoked. This gives you ample time to prepare for the fight beforehand, like by using Psionic Inspiration and other beneficial abilities before engaging the Ethereal. Just be sure you have neutralised any other wandering aliens before attacking them. Make sure everyone has a full weapon and a meaningful turn to work with. When you discover the Ethereal you should take control of the Muton Elites guarding it if possible, they make useful fodder units and provide a fair bit of firepower against the Ethereal. Because of their low Will the Ethereal will often Psi-Lance a mind controlled Muton in preference to attacking one of your soldiers.

To be able to successfully use Psionics against an Ethereal you will need a soldier with a very high Will rating, which can achieved through the use of Psi Armor, Mind Shields, and/or the Psi Inspiration/Combat Drugs abilities, otherwise it has a very high chance to fail. With some or all of those it can be possible to mind control an Ethereal, which is required for the "Xavier" Achievement. Given the difficulty and preparation required, using psionics on Ethereals is impractical for purposes other than the achievement.

All Ethereals have a chance to reflect shots back at the attacker, fortunately for much less than the weapon's normal damage.

A squad at full capacity shooting at the Ethereal will often be enough to bring it down in one turn, though if you're unlucky on reflects it can survive even that.

Sectoid Commander

The Sectoid Commander is a slightly stronger Sectoid with more psionic capabilities. They have much more health than normal Sectoids, but are otherwise unremarkable aside from their Mind Control ability.

• Mind Fray: Causes the target to lose grip on reality, inflicting penalties to Aim, Will, and mobility and doing 5 base damage. Lasts 2 turns, 1 turn cooldown.
• Mind Control: Very difficult psi technique that, if successful, grants control of the target for 3 turns.
• Greater Mind Merge: Merge Minds with all lesser allies of the same species nearby, granting them +25% critical chance and +1 health.
• Enemy Defense: -20% Hit

Weapons Used

Weapon	Damage	Critical Chance	Terrain Damage	Range	Reaction Angle	Reaction Range	Size	Abilities
Sectoid Plasma Pistol	3	0	125	27	200	NA	Small	Unlimited ammo

Sectopod

All of the Sectopod's weapons do area effect damage, so make sure your squad is spread out in order to minimize the damage it causes. Even if an attack from them misses there is still a huge chance it will take out your cover. This makes having two soldiers directly next to each other almost guaranteed disaster, because the Sectopod can fire at one, destroy their cover and fire at the other with no cover bonus. Be sure that any front line soldiers are backed up by Snipers or Heavies.

The Sectopod's overwatch is enabled for each turn it fires its main cannon. In particular this means a Sectopod will not overwatch fire on you immediately after you see it, or on a turn its preparing a Cluster Bomb.

Heavies in particular are brilliant Sectopod hunters. Their HEAT ammo power makes their weapons far more effective against Sectopods. The HEAT ammo also applies to rockets and the Blaster Launcher. A hit from either with HEAT Ammo does 16 or 24 points of damage to Sectopods. A HEAT ammo Bullet Swarm Heavy with a Heavy Plasma can kill a Sectopod in one turn.

After you get Ghost Armor just send a pair of Assaults equipped with it, together with Rapid Fire and Alloy Cannons - you'll need to either hit all 4 shots or get at least 1 critical hit though to kill it. Alternatively, Lightning Reflexes can also replace Ghost Armor to avoid the Sectopod's powerful Overwatch weapon. With Damage Roulette, an Alloy Shotgun, the right abilities, and a hell of a lot of luck, it is possible to "One shot" (rapidfire, but still 1 move) a Sectopod, even on Impossible.

Use suppression to make their attacks less accurate, it will help a bunch. Snipers may also use disabling shot against their weapons. Make as much use of Smoke Grenades, Heavy Cover, and Psionic Fields as you can if you do end your turn within their sights.

Using Plasma / Heavy weapons or Mind-controlled cannon-fodder against this unit is also recommended: an excellent tactic is to MC an alien with high move (like a Heavy Floater) or high HP (like a Berserker Muton), and have them stand point-blank right next to the Sectopod. Since it ignores cover anyways, it will not move before firing it's chest canon. Since the MC'ed alien will receive a full blast out of cover, it will likely receive and die of heavy Critical damage. As the Chest Canon is splash damage, the Sectopod will also receive heavy Critical damage.

If you see Cluster Bomb being prepared, kill the Sectopod quickly or reposition. While Cluster Bomb takes a turn to charge and fires on the aliens' next turn, the Sectopod can move and fire after firing the cluster bomb on that turn. Cluster Bomb has no range limit and can be fired if another alien sees you (like sniper's squad sight, except it doesn't need a line of sight). This means after triggering a Sectopod it should be your first priority, because if you retreat out of its sight range to deal with other aliens first you'll find cluster bombs raining down on you (and without being able to see the Sectopod you can't tell when or where they're coming). While a bit difficult to predict, there are some rare cover situations where the Cluster Bomb can actually be ignored: if cover will intercept all the bombs beforehand (ie, the targeted trooper is indoors, while the 'Pod is outside, they will explode harmlessly on the roof). A Flying unit might also be targeted, only to have the bombs pass harmlessly around them.

Note that, even though their death animation includes a massive explosion, it is not a damaging explosion, like the Cyberdisk's death, and thus, their drones may still be a problem (if a minor one at that) if not taken out the same turn.

Uber Ethereal

Same as the Ethereal, but with higher stats and reflection chance.

Alien Stats Table

Name	HP (Easy/Normal/Classic/Impossible)	Aim	Defense	Will	Movement	Notes
Sectoid	3/3/3/4	65	0	10	12	Target of a mind merge gains one extra health, healed effectively. Increases critical hit chance(+25%) and will(+25) too.
Outsider	3/3/5/5	70	0	20	12	Receives an additional +10 Aim and +5 Movement from bonuses on impossible. Tied for highest accuracy in the game.
Thin man	3/3/4/6	65	0	15	15	Deals 2 less damage on normal/easy
Floater	3/4/4/6	50	0	10	12	Has 35 fuel
Chryssalid	8/8/8/8	Melee	10	120	20	Hardened, Deals +2 damage on classic/impossible, Immune to stunning
Zombie	10/10/10/14	Melee	0	120	8	Deals +2/+4 damage on classic/impossible, Immune to stunning
Muton	8/8/10/10	70	10	10	12
Drone	3/3/5/7	60	10	Mechanized	12	Requires 'Drone Hack' arc thrower upgrade to 'hack', Has 35 fuel
Cyberdisk	16/16/20/20	70	10	Mechanized	18	Hardened while in closed form, Immune to stunning, Has 35 fuel
Sectoid Commander	10/10/14/14	85	20	90	12	+25/35 will on classic/impossible
Muton Berserker	20/20/20/25	Melee	20	80	17	Hardened, Deals +1/3 damage on classic/impossible
Sectopod	30/30/30/30	80	30	Mechanized	12	Hardened, Immune to stunning
Heavy Floater	12/12/14/16	70	10	25	12	Has 35 fuel
Muton Elite	14/14/14/18	80	20	20	12	+10 defense on classic/impossible, +10 additional aim on impossible
Ethereal	20/20/20/25	N/A	40	120	12	Hardened, +25/35 will on classic/impossible
Uber Ethereal	25/25/25/30	N/A	40	150	12	Hardened, +10 will on impossible, Game won upon death

Melee attacks always hit. Hardened reduces critical chance by 60% against the target. (100% if Absolutely Critical is active). On Classic and Impossible, Aliens receive +10 aim and +10 crit chance bonus.