Dwarf multicannon

The Dwarf multicannon is a Ranged weapon. Unlike other Ranged weapons, it is not equipped by a player; rather, it is assembled on the ground. To use a dwarf multicannon, the Dwarf Cannon quest must be completed. The cannon consists of four pieces: the base, the stand, the furnace, and the barrels. After a player has loaded cannonballs into the cannon, the cannon rotates and fires automatically. Cannons are often considered to be a supplement to a primary weapon or fighting method. This is not hindered or affected by the combat style a player uses. Even more so, it seems to be the case that the accuracy of the cannon is dependent on accuracy of the player's current used attack style stats/bonus (be it Magic, Melee, or Ranged).

After completion of the Dwarf Cannon quest, players may buy the cannon parts from the dwarf engineer Nulodion, south of Ice Mountain, for 200,625 coins each. Nulodion also sells the Ammo mould to make cannonballs for 5 coins.

The "Talk" option on Nulodion must be used to obtain the full cannon, whereas the "Trade" option is used to buy the individual parts. If a cannon decays or the mould is dropped, Nulodion will provide a free replacement as well.

A player may own multiple cannons, but only one may be assembled per player at any one time.

Assembly
The Dwarf multicannon is carried in four pieces in a player's inventory. To begin setting it up, the player must place the cannon base on a vacant square surrounded by eight more vacant squares. The rest of the cannon will automatically be set up from there. Finally, the player must use up to 30 cannonballs on the cannon by selecting "Fire." It is rather heavy when each of the four parts are in your inventory, and it will make your weight extremely high. If you do run with it, it is recommended to bring a few Super energy or Stamina potions to compensate for the more rapid energy loss.

There are many locations where the cannon cannot be taken into or cannot be set up, including (but not limited to) the following list. If a player attempts to set down a cannon base in any of these areas, a message will appear in the player's chatbox saying that it cannot be done.
 * Ancient Cavern
 * Al Kharid Palace
 * Barbarian Assault
 * Black Knights' Fortress (in and around): "It is not permitted to set up a cannon this close to the Dwarf Black Guard."
 * Castle Wars
 * Duel Arena (it can be set up in duels; however, will not fire on players and may be lost if not picked up)
 * Dwarven Mine
 * Enchanted Valley
 * Entrana
 * Fremennik Slayer Dungeon
 * Feldip Hills: Red chinchompa hunting grounds
 * Grand Exchange: "The Grand Exchange staff prefer not to have heavy artillery operated around their premises."
 * Ice Mountain
 * Kalphite Queen Lair (Note: While the cannon can be set up in the Kalphite Queen's lair, she will instantly destroy it; see below.)
 * Killerwatt Plane
 * Lair of Tarn Razorlor: "This temple is ancient and would probably collapse if you started firing a cannon."
 * Mort Myre Swamp (this does not include the graveyard, where Dessous is located)
 * Pest Control
 * Player-owned houses
 * Shade Catacombs
 * Shades of Mort'ton
 * Slayer Tower
 * Stronghold Slayer Cave (Area where Abyssal demons/Nechryaels/Waterfiends/Gargoyles are): "The ground isn't very firm around the lake. You can't place a cannon here."
 * TzHaar City, TzHaar Fight Cave and TzHaar Fight Pit
 * Warriors' Guild
 * Waterbirth Dungeon
 * Zogre Burial Grounds

In other locations, the cannon may be set up but may be destroyed by an NPC almost instantly, or is almost useless due to limitations:
 * Certain quest bosses: For example, the Giant Roc will destroy a cannon if the player sets it up within its attack range.
 * The Kalphite Queen, any of the monsters in the God Wars Dungeon, and the King Black Dragon will destroy a cannon if a player attempts to use it.
 * Thermonuclear smoke devil

Mechanics
These are the mechanical aspects of the cannon. This section includes the rotation, targets, and decay of the cannon's parts.

Revolutions
After the cannon has been set up, loaded, and fired, the barrel will rotate and fire at targets within its line-of-sight and range. The cannon barrel rotates in discrete intervals; there are eight directions the barrel may face, and the barrel makes a 45-degree turn every 0.6 seconds (one game tick), completing a full revolution in 4.8 seconds. The cannon fires one cannonball while facing each direction, so it fires up to eight cannonballs per revolution.

In a single-combat zone, the cannon fires at the monster the player is being attacked by. If the player is not being attacked by any monster – not being hit by any monsters – the cannon fires at multiple monsters. This means that a player can range, mage, or halberd from a "safe spot" in a single-combat zone and have the cannon shoot at multiple monsters, as long as the player is never attacked by a monster, in which case that monster will be the only target the cannon attacks. However, the player will need to regularly come out of cover to reload the cannon.

Targets
For each direction the cannon faces during its rotation, there is a specific set of squares relative to the cannon's location that a cannonball may be shot into at that time. This target region can be visualized by a triangle emanating from the cannon barrel. Squares may be cut off from the target region by an obstacle.

Target regions for different directions overlap slightly. This may result in shooting multiple cannonballs at one monster in one cannon revolution, even one that is standing still. Up to two cannonballs may be shot at a monster that takes up a single square per rotation. If it is not in the proper location however, only one, or even zero cannonballs may be shot per rotation.

A cannon set up on (0,0) does not shoot tiles (0,1), (1,0), (0, -1), (-1, 0). Also targets on 16 tiles around the cannon will be shot twice. These tiles are (1,2), (1,3), (2,1) and (3,1) and respectively mirror images of these tiles on other three sides of the cannon. For monsters larger than 1x1 only the southwestern tile is shot. That being said against 1x1-2x2 targets, the worst possible spot to stand is in the middle of the cannon or any corner under the cannon. The best way to slay those is to lure them into a multi-hit spot, or stand far from the cannon. For 3x3 monsters (e.g. Black demons), one should stand under the cannon in the north-east tile (1,1).

Players cannot control what target is chosen, thus it may fire at anything around it. However, if a player is already engaged in single combat, the cannon will only fire at the current opponent and targets between player's cannon and target may prevent the cannon from shooting your target.

Damage and Accuracy
The cannon has a max hit of 30, regardless of the player's Ranged level.

The accuracy, however, is affected by the player's current attack style stats/bonus (Magic, Melee, or Ranged).

Decay
Cannons disappear after a certain period of time being continuously set up. 20 minutes after the cannon has been set up, a message appears that the cannon has almost decayed. 25 minutes after the cannon has been set up, or 5 minutes after the warning message, the cannon will decay. However, the decay timer can easily be restarted by picking up the cannon and re-assembling it again.

The decay effect is not based on the number of cannonballs shot but based on the decay timer as stated above.

The cannon's decay is a one-time event, not a continuous degrading associated with declining performance. The cannon is equally effective at all times.

Loss
Cannons that do decay are not lost forever but rather may be re-obtained for free from Nulodion (it does not matter if you bought it from another player or from Nulodion himself). The fastest way to get to Nulodion is to cast Lassar Teleport (an Ancient Magicks teleport). Alternatively, players may teleport to the monastery using a charged Combat bracelet and run to Nulodion, or they can choose to run from Edgeville or Falador. Finally, one can use a Skull sceptre to teleport to Barbarian Village and run north-west to Nulodion.

If you log out while your cannon is set up, you can retrieve it back free of charge.

Cannons will also disappear right away if they are set up and then the player switches worlds. You can get them back from Nulodion in the same way as when it decays.

If a player dies while a cannon is set up, the cannon stays set up at the location. After it decays, it may be re-obtained for free from Nulodion. It is a common belief that cannons are lost upon death, but in this case, the cannon may easily be re-obtained for free.  WARNING:  You cannot re-obtain a cannon that was in your inventory if you are killed in the Wilderness.

 WARNING:  If a player dies while a cannon, cannon parts, or cannonballs are in the inventory, these items are lost unless the player is able to run back to where they died. If you are under attack by a strong enemy that may kill you, immediately set up your cannon. If you do die, you won't lose your cannon.

If the cannon itself is destroyed in combat, the player can re-obtain a new dwarf multicannon from Nulodion, free of charge. Monsters that destroy the dwarf multicannon are bosses. (Example: King Black Dragon, Kalphite Queen, and many more.) However, a cannon can be used to kill the Chaos Elemental.

Nulodion will not hand out a replacement cannon if the cannon or cannon parts are banked, set up, sold, or dropped. Replaced cannons come loaded with cannonballs equal to the amount loaded in the cannon when the cannon was lost.

Usage
Cannons are commonly used by players training Slayer to speed up tasks. With the average price of cannonballs, the use of a cannon is often considered to be quite expensive. However, the cost is often considered to be justified by the bonuses of using a cannon. A player doing a Slayer task can melee almost the entire time getting nearly as much Melee experience as they would without using a cannon. The cannon will also attack several targets even in a single-way combat area as long as the player is not under attack (e.g. in a safe spot).

In crowded areas, such as the Dagannoths under the Lighthouse, the cannon may produce a level of mayhem usually only achieved with Ancient Magicks spells. However, in highly populated areas, the player will need to remain almost constantly by the cannon in order to reload it because large numbers of cannonballs will be needed. Also, they will probably get negative feedback from other people fighting.

Trivia

 * The only ammunition for cannons that players can use is cannonballs made from steel. However, Dondakan from the quest Between a Rock... fires adamantite, runite, and gold cannonballs from his cannon.
 * If the cannon is fired in a single-combat area the chat will say, "I'm currently under attack" along with an occasional, "Someone else is fighting that" depending on the combat status of the player-character.
 * If a player drops the components of the cannon set, they will discover that the items are 1x1 size, despite the cannon being 3x3.
 * The cannon may sometimes shoot through walls.