Man cannon

A man cannon, more formally referred to as a conveyor lift, is a device that launches an individual or object through the air over a long distance. In the case of human-built man cannons, this is typically accomplished by means of some form of air vent or jet thruster, whereas Forerunner or Covenant man cannons commonly employ more sophisticated technology, such as anti-gravity emitters similar to that used in gravity lifts.

Design and function
Although they come in various designs and configurations, man cannons typically resemble air vents which emit a stream of exhaust that applies a strong force to anything that enters it. The distance an object is launched depends on the mass of the object and the strength of the cannon; human-sized objects will usually be catapulted many yards, while heavy vehicles and other large objects have considerably shorter trajectories.

Gameplay
The man cannons were introduced as gameplay objects in Halo 3, and returned in Halo: Reach, as well as in Halo 4. In many maps, they replaced teleporters as a means of quickly moving across long distances, similar to how gravity lifts propel the player over a vertical span.

The user is unprotected while in mid-air, but can still attack other players. The danger of using the man cannon is that the user's trajectory is set when they enter. Since the person being propelled through the cannon does not have a lot of air control, an enemy sniper will be given a good amount of time (the main man cannon on Valhalla takes around 2.5 seconds from 'take-off' to 'landing') to estimate where your head will meet his crosshairs. It also adds some advantage, as this player still can attack the other competitors. The player also has a quick overview of the positions of enemies and the current battle situation.

As of now, man cannons have only been featured by default in the Halo 3 multiplayer maps Valhalla, Guardian, Narrows, and Avalanche. They also appear as a placeable object via the Forge in almost any other multiplayer map.

Placeable Man Cannon
The man cannon has only appeared in Halo 3 as an environmental feature in 4 maps so far, but a placeable version of the man cannon can be placed manually in Forge on Rat's Nest, Foundry, Standoff, Avalanche, Cold Storage, Sandbox, Longshore and Citadel, although in other maps a grav lift could be used to similar effect, albeit not as powerful or directional.

This placeable version produces roughly the same amount of motive force, but can be placed anywhere on the map and in any position. This gives users great creative potential when using the man cannon in Forge that can be utilized to produce maps with better gameplay than would otherwise be possible. The man cannon is also an object which is immovable during normal gameplay after being placed in Forge. Unlike the small portable gravity lift, the man cannon cannot be destroyed. Until Halo 4, all placeable man cannons were Covenant ones, but Halo 4 features human-made man cannons.

Tactics

 * The main man cannon on Valhalla has a 'landing zone' roughly the size of an 'Elephant', but a good player will quickly see where his opponent is about to land. This makes it harder to pinpoint where the player will land, although on some maps such as Narrows, the LZ is considerably smaller to the point that you can place a Trip Mine to much effect.
 * Throwing a grenade (Plasma Grenades work best) or Power Drain into the Man Cannon can sometimes be effective against opponents within range.
 * You can improve the distance of your Man Cannon jump by pressing the jump button as you land. Some of the momentum left from your launch will transfer and allow you to leap farther. This is best accomplished by walking directly into the center of the Man Cannon you are using and mashing the jump button as you land. This will give you several smaller jumps until you return to normal speed. Jumping into the mancannon usually does not give you as much forward momentum, so it will not work. This trick is useful on Valhalla when getting the Spartan Laser. You can jump all the way across the river on the Lake Base side, or past the large rock on the Waterfall Base side.
 * Almost anything can be launched through Man Cannons. It's an effective way for supplying teammates across the map with guns, throwing equipment to use on friends or enemies.
 * Dropping Flares into the Man Cannons on Avalanche in Custom Games is an effective way of using optical cover to invade a base.
 * Throwing Bubble Shields into the Man Cannons is an effective way to protect your flag carrier in the air, and while waiting for a Hornet or other transport to arrive.
 * Explosive objects, such as Fusion Coils, will almost always explode upon impact of landing after being launched from a Man Cannon. Doing this can basically give your team a sort of improvised mortar (particularly in Valhalla in Custom games).
 * In Valhalla, it is useful to fly a Type-32 Ghost into a Man Cannon while simultaneously activating the boost. This will send the Ghost completely across the map, albeit somewhat beat up or completely destroyed upon impact of landing.
 * Though it requires amazing timing and a degree of luck, it is possible to hijack an incoming enemy Banshee or Hornet, preferably from the side of the vehicle. This action can easily turn the tide of a game. But note that this is nearly impossible if you attempt to hijack head-on, as the speed which you are moving can easily get you splattered.
 * In CTF games on Valhalla, the man-cannon is an essential tool, that can get your player with the flag almost halfway across the map.
 * It is possible to launch a mongoose through the man cannon and get the "Mongoose Mowdown" achievement by doing this, particularly on Valhalla and Avalanche.
 * If Man Cannons are set face to face, you have to be careful since you cannot escape if an enemy player on the other side throws objects in, resulting in an undodgeable collision and instant kill. Using an object to kill may reward a splatter kill.

Trivia

 * The Man Cannons placed in Valhalla and Narrows can be shut down if you use the map Overload Glitch. This makes it a lot easier to place objects such as spawn points, grenades and teleporters close to or even on the Man Cannon. If the round or game is ended the map is no longer overloaded and thus, activates the Man Cannons again.
 * Using the Man Cannon to throw large objects can be fatal to opponents. Doing ten straight kills this way without dying, strangely, will award the player the Vehicular Manslaughter medal.

List of appearances

 * Halo 3
 * Halo: Reach
 * Halo 4
 * Halo 2: Anniversary
 * Halo 5: Guardians