Here are a couple examples to describe the mechanics of Armor Class versus Damage Resistance.
Master Shogo boldly kicked down the door leading to the crypt of Amox'zil, the Scourge of Ferrell. "I have waited to battle you for a long time," Shogo said to the ancient mummy warrior upon his throne. "In the name of Dagath, I shall destroy you!"
Shogo leapt forward with a flurry of blows, relentlessly pummelling Amox'zil with hands and feet. At the first opportunity, the Scourge of Ferrell swung his mighty Greatsword of Doom at Master Shogo. Seeing the blow coming, Shogo sidestepped it and returned with a blow of his own.
Master Shogo has a pretty good Armor Class. When Amox'zil swung his Greatsword of Doom, his attack roll failed to overcome Shogo's Armor Class and thus Shogo took no damage. What Armor Class represents is
damage avoidance, the likelihood of not taking any damage in the first place. Armor Class is derived from many things; see your NWN manual for details.
"Har har har!" Amox'zil chuckled as the melee continued. "Your pathetic blows cannot harm me!" Shogo backed off, assessing his foe. Indeed, it seemed that Amox'zil had taken no damage at all from his bare fists.
"Your body is strong, but your form is weak," Shogo replied. "Let's see how you fare against my Crypt Reaper!" The monk brandished a gleaming kama from behind his back and sprung forward to cut down his mummified foe.
Many undead are strong against certain physical attacks. While most are weak against bludgeoning attacks like Shogo's fists, Amox'zil seemed to take little or no damage at all. Amox'zil has high Damage Resistance versus Bludgeoning, a form of
damage mitigation. After Amox'zil fails to avoid a blow (his Armor Class is insufficient to consistently avoid Shogo's attacks), he can count on his high Damage Resistance to prolong the fight.
When Shogo became wise to this situation, he switched to his Crypt Reaper, a magical kama that does Slashing damage and does additional Positive Energy damage. Since undead usually take double damage against Positive Energy, this will certainly spell doom for the nasty mummy.
Hope this helps!
