Cannons are dangerous, if sometimes unpredictable, weapons whose manufacture is limited to human and Dwarf experts. When they work, cannons can shatter the most determined enemy, pouring deadly shot into his massed formations, leveling his cities and toppling huge monsters. But cannons often go wrong. Weaknesses in the casting methods can leave minute cracks or other deficiencies which cause them to explode when fired, or gunpowder can fail to ignite or may explode prematurely. Despite the occasional spectacular accident, cannons are extremely potent weapons that have been instrumental in winning more than one battle on behalf of their users.
Cannons are fired in the Shooting phase. To fire a cannon, it must first be turned on the spot so it points in the direction of the target which must be within line of sight but otherwise is not limited by targeting restrictions. Then the player must declare how far the cannon is going to shoot - eg, 24", 30", 32", etc.
The cannonball travels the distance that the player has nominated, plus the score from the Artillery dice. Roll this dice and add the score to the distance that has been declared. The cannonball travels the total distance towards the target and will either land short, pass straight over, or hit depending on how accurately the player guessed the range and what effect the dice has.
Remember the dice will always add at least 2" to an estimate, and can add up to 10", so you should aim a few inches short of the target.
Once it is established where the cannonball hits, place a small coin or other marker directly over the spot. The cannonball does not stop where it hits the ground but bounces straight forward and cuts a line through any targets in the way. To determine how far the cannonball bounces, roll the Artillery dice again and mark the spot where the cannonball comes to land. Any models between the points where the ball strikes the ground and where it eventually comes to land are hit by the flying cannonball. This line is considered to be a template for rules purposes (such as "Look out, Sir!" rolls).
When a cannonball collides through a unit, only one model per rank is hit. The diagram below shows how this works.
Any model struck by a cannonball takes a Strength 10 hit resolved in the normal manner. If the cannonball wounds its target then it causes not 1 wound but D3 or D6 wounds depending on the size of the cannon. As most models have only 1 Wound anyway it will not be necessary to roll this extra dice, but it is important when it comes to rolling for heroes, big monsters, and engines of war which can take several wounds. Wounds caused by cannon shot cannot be saved by armour. If a cannonball hits a model which has several parts then resolve which part of the model is hit just like shooting with bows, etc.
No armour saving throw is permitted for wounds caused by cannons. If a cannonball hits you, no amount of armour is going to do you any good. Ward saves can be taken as normal.
For example: A cannon is fired at a unit of Goblins that is in front of the player. He makes his guess and declares that he is aiming 12" directly towards the middle of the Goblin unit. Having made his guess the player then rolls the Artillery dice and scores a 4, which equals 4". This makes a total of 16". He measures 16" towards the Goblins and places a marker where the ball hits. If he has guessed well this will be just in front of them. The ball now bounces forward the score of the second Artillery dice roll. This time he rolls an 8 and the ball bounces 8" straight through the Goblin unit hitting all the models in the way.