|“||The Arc Thrower is a non-lethal sidearm designed to stun hostile targets. The mechanism seems to be most effective against weakened enemies.||”|
– Engineering description, XCOM: Enemy Unknown
Prerequisites: Arc Thrower Research
Production Time: Immediate
- 5 Engineers required
Uses per mission: 2
The Arc Thrower can be used to stun and capture all biological aliens with the exception of Chryssalids and Zombies who are immune. Robotic enemies such as Cyberdiscs, Sectopods and Drones are also immune; Drones can be "hacked" granting full control over them for the duration of the mission after the appropriate upgrade is completed (see below). The chance to stun rises as the target is brought under 4 HP:
|Chance of Success||49%||70%||80%||90%|
In the expansion, XCOM: Enemy Within, Seekers and Mechtoids are also immune to the Arc Thrower. Additionally any EXALT agent stunned by an Arc Thrower will immediately commit suicide rather than be captured.
The Arc Thrower can be upgraded by several Foundry Projects:
A fully upgraded Arc Thrower receives improved stun chances up to 6 health points, can hack enemy Drones, and repair S.H.I.V.s. While each of these upgrades originally maintained separate charges, as of Update 3 the Stun, Hack Drone and S.H.I.V. Repair abilities granted by Arc Thrower now share the same use count: if your soldier stuns an alien and then hacks a drone, that Arc Thrower will not be able to stun another alien or otherwise be used again during the mission.
Percentage chances of stun for the Improved Arc Thrower:
|Chance of Success||49%||70%||75%||80%||85%||90%||95%|
Percentage chances of stun for the Improved Arc Thrower in XCOM: Enemy Within:
|Chance of Success||49%||70%||80%||90%||95%||95%||95%|
- Despite the in-game description, the Arc Thrower is not a pistol, and instead occupies an item slot.
- Also counter to the in-game description, the Sniper's In the Zone ability applies to a successful stun, allowing them to retreat to cover afterward.
- Captured aliens can be interrogated, potentially granting valuable research projects or credits. Of equal importance is that stunning aliens also captures their weapons intact. For example, stunning a Muton can yield a Plasma Rifle and an Alien Grenade, two of the best weapons in the game, at the end of the mission.
- Capturing a Muton in the early in the mid game phase enables the squad to access these weapons more quickly than usual. The Alien Grenade is particularly useful in the mid game phase and only needs the completion of the Foundry Project to make unlimited quantities available.
- Prior to building the Alien Containment, aliens cannot be captured. Aliens can still be stunned with the Arc Thrower to aquire other drops, such as the light plasma rifle from Thin Men. Outsiders can also be stunned to aquire the outsider shard, even without building an alien containment.
- Aliens captured alive can be interrogated and then autopsied afterwards, netting you both research projects.
- Early in the campaign, it might be advisable to give it to a Heavy soldier, since early on their primary weapon spends ammunition at a rather alarming pace, and has no secondary weapon. Later if encountering more closed quarters stun opportunities a Sniper may be a better candidate for the Arc Thrower, especially if the Heavy's low starting ammo is no longer an issue because of Ammo Conservation. After all aliens are captured and there's a sufficient supply of plasma weaponry available, the Arc Thrower can be equipped as a longer-ranged two-charge Medikit for MEC Troopers as long as S.H.I.V. Repair has been researched. This is especially useful on Support troops with Deep Pockets, who can use the Arc Thrower three times.
- With a range of 3.5 tiles, the Arc Thrower forces your soldiers to potentially expose themselves to a world of retaliatory pain should the stun fail. It is therefore recommended to have the rest of the squad ready with one or more backup tactics:
- Reduce the lethality of the enemy, such as Disabling Shot, Suppression, or using items such as Flashbang Grenades. Note that Disabling Shot has a bigger chance to miss due to its Aim penalty, and that Suppression may not be enough to stop a shot at higher difficulties, not to mention the fact that a hostile that is low on health might die from a direct hit from a Suppression reaction shot. If in doubt, applying multiple stacking Aim penalties on on top of each other, and approaching in Cover, maximizes (though will not guarantee) the safety of the XCOM soldier tasked with deploying the Arc Thrower.
- Boost your soldier's survivability with Smoke Grenades or a Telekinetic Field. This does not guarantee that the enemy will miss, but it is better than nothing if the enemy cannot be disabled or killed. Note, unlike the Telekinetic Field, the Smoke Grenade adds defensive bonuses to friend and foe alike.
- Kill the target. As this method prevents the enemy from being captured by a successive stunning, this is action is best considered only when the above options are unavailable or the intended stun target presents an extreme threat if not neutralized; the Berserker offers a unique challenge to stun as any soldier failing to do so with the Arc Thrower will be within movement range of this alien's deadly melee attack which is not affected by Aim penalties.
- Uncovering/activating alien packs is also another potential issue during capture attempts, as a soldier equipped with an Arc Thrower will often need to cross considerable distances to get to the target, possibly leading to unwanted and unexpected engagements, especially on smaller maps. Employing the aforementioned tactics can mitigate such threat, which can also be circumvented entirely with the use of intel gathering tools such as the Battle Scanner ability, Ghost Armor and the Hyperwave Relay.
- Stunned and unconscious Aliens can still be accidentally killed if caught within radius of an area-effect attack, such as a player's grenade or rocket explosion, or the area-effect attacks of other aliens.
- It can sometimes be difficult to lower an enemy's health without outright killing it. The player should use weapons with fixed, non-random damage output to lower the enemy's health in a controlled manner. For example: Frag Grenades and Needle Grenades deal 3 damage, Alien Grenades deal 5 damage and Disabling Shot deals 1 or 2 damage, Collateral Damage Deals 1-3 damage depending on the weapon used. (Note: these are the basic damage amounts not reflecting such modifiers as Reaper Rounds, Shredder Rocket, Grenadier, Mayhem, Aggression, Bring Em On, Killer Instinct, Gunslinger, or Vital-Point Targeting.) Alternatively there is the totally tech level dependent ability Flush. Essentially any attacks with non-random damage are useful here (allowing the player to reach the desired specific health level via simple arithmetic); even Rocket attacks can be used, against high-health enemies.
- Another good option for controlled enemy health-reduction is to switch to pistols for a more controlled damage output before stunning, but this can also be altered by Pistol Upgrades. Of course, non-conventional pistols may also be used to circumvent the upgrades, which also neglect Reaper Rounds.
- Stunning Sectoids who are in the process of transmitting Mind Merge does not kill the receiving unit.
- In XCOM: Enemy Within, stunning an EXALT member and causing them to suicide will grant the "Pain in the Neck" achievement.
- Stunning Heavy Floater provides Meld, but it does not provide Weapon Fragments.
- Soldiers can stun aliens that are on different level above ground than them. For example, soldier standing on ground can stun Floater in air.