The Cannon can be used defensively behind Crown Towers to help defend against melee troops.
Cannons can be effectively destroyed with flying air troops, such as Minions, Balloons or a Baby Dragon to demolish the defensive Building, without the player's troops being targeted.
As with any defense, it is not wise to play the Cannon proactively, as this may for example, allow an opposing Royal Giant or Musketeer to out-range it, destroy it, and then attack the player's tower.
The Cannon is best placed in the radius of the user's Crown Towers, to prevent flying troops such as Minions from destroying it without any issues. As such, if a Cannon is ever placed out of range of the Crown Towers, the attacking player can use air troops to destroy the cannon unhindered.
The Cannon can be very useful for taking down Barbarians or a Hog Rider if placed in the right area, gaining an elixir advantage. A Cannon combined with an X-Bow or Inferno Tower can wreak havoc on high-hitpoint troops.
It has a short range so placing it beside the Arena Tower will render it useless against ranged troops like Spear Goblins, Archers, and Musketeers.
As said before, keep in mind that Musketeers and Royal Giants can out-range the cannon, so be careful when using the Cannon against those troops.
The player can, however, place the Cannon while the ranged troop is in the range of the Cannon to prevent ranged troops from out-ranging it.
The Cannon can also make a great distraction for dangerous troops like the Prince and the Balloon. The Cannon can take out an X-Bow that is trying to take out your tower but isn't very quick at doing so.
It is good against tanks; place it 4 tiles away from the river and two tiles away from the Arena Tower to pull it with the maximum distance.
For troops that only target buildings, place it 4 tiles from the river and 3 tiles away from the Arena Tower.
But the building would need to be placed 4 tiles from the river and 2 tiles from the Arena Tower if the opponent executes a push that includes a Hog Rider.
The player can use it to aggro building-target only troops after it crosses the bridge but only if it haven't travel more than 2 tiles from the bridge or it will go straight to the Arena Tower.
For Royal Giants, place the building 3 tiles from the river and 1 tile from the Arena Tower.
Alone, the Cannon isn't a very effective counter, but it is possible if combined with any other unit.
Make sure to place it reactively or he will out-range the Cannon.
If a Balloon is placed on the very edge, you have to place it 4 tiles from the river and 1 tile from the Arena Tower. If a Balloon is placed on the very edge in front you can place it 3 tiles away from the river and 2 tiles away from the Arena Tower. If a Balloon is placed right on the path, you can do the usual building place (4 tiles from the river and 3 tiles from the Arena Tower). The Lava Hound behaves slightly different: if it's placed on the very edge it has to be 3 tiles away from the river and 1 tile from the Arena Tower. And if it is placed on the path the player must place it 4 tiles away from the river and 2 tiles away from the Arena Tower.
These building placement rules apply to all buildings; even though the Tesla is smaller than all buildings, the same rules still apply.
The Cannon was added with Clash Royale's soft launch on 4/1/16.
On 2/2/16, the February 2016 Update decreased the Cannon's Elixir cost to 3 (from 6), its range to 6 (from 7), its lifetime to 40 sec (from 60 sec) and decrease its hitpoints by 55%.
On 23/3/16, a Balance Update decreased the Cannon's lifetime to 30 sec (from 40 sec).
On 3/5/16, the May 2016 Update decreased the Cannon's hitpoints by 11%. This update also fixed the "range bug" and decreased the Cannon's range to 5.5 (from 6) but its effective range is unchanged.