Unit parameters and special abilities play a heavy role in combat. "Attack" is matched against target's "defence" to determine whether a hit was scored, and then "damage" determined the number of hit points the target loses. Some offensive spells have to beat the target's "resistance" instead, or even both "defence" and "resistance". Physical attacks (such as "archery") target defence, while other attacks (such as "venomous spit") target resistance. Equal values of the attacker and the defender parameters results in a 50% chance to hit, and for each point of difference this is changed by 10% (but to a minimum of 10%, or a maximum of 90%). While most commonly only physical damage is dealt, sometimes attacks are partially or fully magical in nature, and can result in additional negative effects on the target: a fire strike has a chance of setting the target aflame, a lightning strike can paralyse the target, and so on. At the same time, units often have protection and/or immunity against specific forms of attacks. Protection reduces the damage of that effect by 50% e.g. "lightning bolts" with "marksmanship II" (a skill to improve attack/damage of a ranged attack) has 7 attack 4 damage, but would do a maximum of 2 damage against a unit with "lightning protection", and none against a unit with "lightning immunity".