M-920 Cain

The M-920 Cain is a heavy weapon from Mass Effect 2.

In-Game Description
The effectiveness and efficiency of mass-effect-based weapon technology has rendered large-scale deployment of highly explosive weaponry all but obsolete in infantry weapons.

Normandy's scientists have prototyped a modified version of traditional high-explosive rounds that is applied to a 25-gram slug. When accelerated to 5 km/s, the round is devastating. Though a technically inaccurate label, this prototype weapon is nicknamed the "Nuke Launcher," and its high-explosive matrix generates an archetypical mushroom cloud on impact.

It inflicts high damage with large area of effect. Very effective against armor, shields, and barriers.

Acquisition
Unlocked at the Normandy research station after three Heavy Weapon Ammo upgrades have been researched. Costs 25,000 iridium.

Player Notes

 * On Normal difficulty, the M-920 Cain is capable of killing enemies within an extremely large area in a single shot (do not fire the Cain in a small room, as this can backfire and result in the player's death). The Thresher Maw on Tuchanka, the Oculus, and the final boss are the only enemies in the game that the Cain cannot kill instantly; instead, the Cain takes off a little more than half of each enemy's health bar. On Insanity difficulty, A-61 Mantis Gunships, Praetorians, YMIR Mechs and the Geth Colossus also will not die in one hit, though each will have very little armor remaining.
 * Gathering all the heavy weapon ammo you can find will generally allow it to be used once every other mission. However, the Cain can only be fired when its ammo count is at 100% or above, meaning that it can only hold enough ammunition to be fired twice (full ammo upgrades, a 10% ammo bonus from armor, e.g. from the Cerberus Assault Armor set or the Ordinance Packs sold at Harrot's Emporium, bring its maximum capacity to 215%, or two shots). Shooting the Cain twice in succession will cause it to skip the usual charge time to fire the second shot.
 * The Cain's capacity to fire only a single shot makes it a questionable choice for missions early in the game, as other heavy weapons are less ammunition-intensive, allowing them to be used throughout an entire mission rather than only once.
 * After five Heavy Weapon Ammo upgrades the ammo will "refill" automatically after each mission you use it on provided it is equipped at the end of the mission, however it only fills up to 100%. This effect is not reliable. It either doesn't work on certain missions, or there are other unknown factors at play.
 * On Normal difficulty two shots are enough to defeat the final boss and Thresher Maw.
 * Although the game claims that the slug is sped up to 5 km/s, the actual projectile in game moves very slow compared to other weapons. This can actually make it difficult to hit enemies that move and dodge a lot, such as the final boss.
 * The use of the M-920 Cain is questionable because of the ammunition consumption. It is very difficult to get ammunition needed during the mission with it. M-920 can really only be used through planning, with heavy ammunition being built up prior to the M-920 Cain's use.
 * The Cain cannot be charged while in cover, and charging while in cover will cause you to pop up out of cover. With a four second charge time, this can mean certain death if you aren't careful, especially on harder difficulty settings. This can be compensated for by finding a tall piece of cover (like a stack of crates, or a column), standing behind that cover (but not going into it), begin charging, and then strafe out of the cover to fire the shot, then ducking back in.

Trivia

 * The M-920 Cain is the only heavy weapon available for research that does not unlock a codex entry. However it appears that there was a Codex entry for the Cain that was cut before the game's release.
 * After having been unlocked it does not appear on an Armory table like the rest of the heavy weapons do.
 * The real world equivalent is the Railgun, which has clocked speeds at over 2.4 kilometers per second, with a projectile weighing in at 3.2 kg / 7.0547 pounds.