Critical hits occur when a character rolls a natural 18 or higher and hits the target by a margin of 5 or more after all adjustments. If the character scores a critical hit, he inflicts double damage dice, calculated before adjustments for strength, magic, or special circumstances.

Concealment and cover work only against missile fire; cover also provides a bonus to saving throw rolls where an effect causes physical damage, like a fireball spell.

The amount of the target that is concealed or covered determines the penalty to any missile attacks made against the target.

A figure's line of fire is considered to run from the centre of its square to the centre of the target's square. If the line of fire passes through any part of a square containing an obstacle, the target is considered to be covered or concealed to some extent. The DM can decide whether the target is 25%, 50%, 75%, or 90% screened, or he can roll randomly if it is not clear. If the line of fire passes through a square containing a figure engaged in melee, the archer must use the rules for firing into a melee to determine where his shot goes.