When you shoot at a character riding a large monster the usual target restrictions for shooting at characters apply. However, monsters are so big that the chances of their being able to shelter in a unit of smaller-sized troops are rather slim. This means that a character riding a big monster is easier to pick out as a target. Because the monster is a large target the enemy adds +1 to his to hit score. The normal -1 to hit that applies to characters on foot or as cavalry does not apply to characters riding monsters. The monster is simply so big that there is no doubt as to where the character is! You may wish to reread the rules for shooting at characters in the Heroes and Wizards section.
When shooting at a large monster and its rider roll to hit as normal, adding +1 because the monster is a large target. Once you have established how many hits have been scored you must apportion them between the rider and the monster. For each hit scored roll a D6:
D6 Score | Hit |
1, 2, 3, 4 | The Monster - roll to wound the monster as normal. |
5 or 6 | The Rider - roll to wound the rider as normal. |
Work out wounds separately on either the rider or his mount. Take any saving throws due to the target as normal. Most monsters do not have a saving throw as they have no armour, but some have scaly hide which confers a separate save. Riders may save for their armour, but remember they do not receive the additional +1 as do cavalry riding smaller creatures.