(Attack vs. Defense, Attack vs Defense, AttackvsDefense, Attack versus Defense) abbv. Attack versus Defense. A number which represents the advantage (or disadvantage) an attacker has due to the type of weapon they are using, versus the type of base armor the target is wearing. For example, rapiers do well against unarmored or lightly armored foes, and thus wielding a weapon against such a foe will result in a sizable boost to your chances of scoring a hit that will not be deflected by your target's armor. On the other hand, rapiers do very poorly against rigid leather and plate type armors, so they may actually receive a penalty against such armor types. A broadsword has a more "rounded" AvD against most armor types, which is not as high against unarmored or lightly armored foes as a rapier, but fares much better against heavier armor types.

See also: AS, DS.