The Cannon Cart is a single target ground troop that is a cannon on wheels.
Cannon Carts have no preferred target when attacking; they will simply attack the closest building to them. However, once they become aware of enemy Guard Post troops (either by being attacked themselves or being near another friendly troop under attack), they will leave their previously targeted building and engage the enemy troops instead. Once all of the nearby enemy troops are defeated, they will proceed to attack the nearest building from their current location.
The special ability Last Stand, unlocked at level 2, allows it to continue shooting with temporary hitpoints after its health bar has been depleted, but immobilizes it. The additional health would also slowly deplete. In its ability, it can shoot further than normal.
The Last Stand ability may cause the Cannon Cart to target another building from what it was shooting before it got destroyed.
Try to place a tank, such as the Boxer Giant or Battle Machine, to take shots for the Cannon Cart while the Cannon Cart wrecks havoc behind.
The Cannon Cart has a high damage output but relatively low hitpoints, which makes them vulnerable to the Multi Mortar, so try and spread your tanks from the Cannon Carts so splash damage cannot hit both of them.
The Cannon Cart can shoot over two-tile gaps between Walls and a Building, which many players do to prevent Sneaky Archers from shooting over.
The Cannon Cart can quickly destroy the Crusher and other key defensive buildings to make a path for their tanks.
Keep Crushers away from areas where Cannon Carts may be deployed. Its long range will render the Crusher useless, thus allowing Boxer Giants, Raged Barbarians and the like to easily swarm a good portion of the base.
It's best to ensure that the Cannon Cart is destroyed as quickly as possible in order to prevent it from potentially devastating the base. To do this, it is best to quickly destroy any troops that might be able to protect the Cannon Cart. Since the Cannon Cart is often paired with Boxer Giants, one could find Crushers and Spring Traps useful. A Double Cannon is a versatile substitute, being able to do lots of damage to tanks; it can also destroy a relative leveled Cannon Cart with a single burst.
The Multi Mortar can deal damage to both the Cannon Carts and their tanks with its splash damage. Try to protect it in the center of your base to maximize its effects, as it can destroy a cannon cart with two volleys of shots.
Try and place buildings around your base so it is harder to make a funnel. Since most Cannon Cart users have no expendable unit in their army, they have to expend at least two Cannon Carts to funnel the rest of the units in.
At level 1, the Cannon Cart appears to be a cannon tied to a wooden cart by rope.
At level 5, the Cannon Cart is no longer supported by ropes, and looks like a normal Cannon but with a bigger base.
At level 9, the Cannon Cart now has a bolted ring around its center and looks darker.
At level 13, The center and the last ring of the cart have now turned to gold. It also slightly changes colour.
Of all available Builder Base troops in the game, it has the highest damage per second, disregarding any of its abilities and damage bonuses.
A battle does not end when a Cannon Cart is in its Last Stand, even if it cannot shoot any other buildings.
It is currently the only Builder Base troop that isn't a variant of a Home Village troop, except the Bomber and Drop Ship, although they are similar to the Wall Breaker and Balloon.
In the 25/8/17 Balance Update, the Movement speed was increased by 33% (from 12 to 16), the First shot is fired after 0.4 seconds (speed increased from 1.2 seconds) and the range of Cannon Cart’s Last Stand ability was increased by 1 tile.