I've been wrestling with the idea of Defense for a long time now. The concept comes from Spellcraft & Swordplay, which, in turn, takes it from OD&D. The base idea is that magical armour and shields don't affect Armour Class, but rather levy a penalty to incoming attacks. That mechanic disappeared as the idea of Weapons vs. Armour modifiers were dropped; at that point, Armour Class became simply a defense number, so it was easier to have armour and shields just change the AC. Since S&S keeps the Weapon vs. Armour table, it makes sense to keep the original mechanic.
But, S&S doesn't give the mechanic a name and I have expanded upon the concept in Dying Sun. First, I think shields are criminally undervalued in Ye Auld Game. I won't rehearse the argument; suffice it to say that there is a reason that most people don't enter hand-to-hand combat without something to hide behind. So in Dying Sun, shields gives a Defense of +2. A fighting-man can use an off-hand weapon to parry instead, gaining a +1 to Defense, but only against melee weapons (you can't parry arrows except in super-hero games).
Something was still bothering me, though. And then, I got involved in a discussion at rpg.net about the game Atlantis: the Second Age. And that reminded me that I really liked the idea from Talislanta (the base system) in which a character's weapon skill not only adds to their combat roll, but subtracts from an opponent's roll. And that caused me to figure out what was bothering me: Defense was too unconnected to character. It reminded me that I had added a house-rule to the very AD&D-based system in the Arcanum (the predecessor to A2A) in which weapon bonus functioned similarly. So, anyway, that all prompted this rewrite:
Defense is a penalty levied against incoming attacks. Defense equals the Attack Bonus from Class and Level. Thus, a 4th level Slayer with 2+2 Attacks has a Defense of +2. Monster Size can also grant a Defense.
Shields grant a +2 Defense versus all incoming attacks and may add to DEX Throws for area-effects attacks and the like. As with other armour, most shields are made from natural materials and break when they take a hit from a roll of boxcars (see Critical Hit). If a character is wearing natural armour as well as using a natural shield, assume the shield breaks first.
Bronze shields work as normal. A steel shield adds an additional point of Defense, making +3 in total.
A combatant may use a small, parrying weapon in the off-hand instead of a shield. This grants only a +1 to Defense versus incoming melee attacks and none versus missile attacks. It does, however, give the character 1 extra attack with the off-hand weapon at -1 to the Combat Roll.
In turn, that prompted me to think Survivors. I felt that while Slayers ought to be the best at actively defending, Survivors ought to be good at just getting the hell out of the way. And so I write down the following this morning:
In addition to the usual ways in which in a character is protected during a fight, he may also choose a full-bore defense by dodging. The character declares his intent to dodge during the Declaration Phase of the round. Dodging means that the character gets no attacks - Melee, Missile, or Sorcery - as dodging essentially replaces those actions. He does get a half-move exactly as if he had attacked. Note that the dodging character must have at least ½ of his Movement Rate to dodge; otherwise he is too encumbered to move fast enough.
Any time the dodging character is attacked during the round, he is allowed to make a DEX Throw to avoid the attack. If successful, the dodger avoids the attack entirely; if unsuccessful, the attack proceeds as normal.
The Referee should feel free to add modifiers to the dodge throw. A more balanced system, would allow the attacker’s degree of success to function as a penalty to the dodging DEX Throw. So, if the attacker rolls “13”, the dodge roll takes a -2 penalty. This ruling is more fair to the attacker, but adds complexity. Alternately, one might use the attacker’s combat bonus as a penalty instead. So dodging an attack from a 5th level Slayer is always at -2. The Referee might also apply a penalty to consecutive dodges with each dodge after the first adding a cumulative -1 penalty; this would reflect the idea that a combatant can only really evade so much in the 5 seconds of a combat round.
As always, thoughts welcomed.