With D&D going more and more to static numbers for saves and defense, especially in the Fourth Edition of the rules, I know I’m swimming upstream with this suggestion for Third Edition DMs.
All the same, here it is: I think defenders should roll for their Armor Class, and thus, oppose the roll made by the attacker.
After all, the use of opposed rolls is a key component to 3.x rules. A Bluff check is opposed by a Sense Motive check and a goodly many spells are opposed by some sort of Saving Throw. Opposed rolls are an excellent mechanic, because they eliminated the need for a whole host of comparative result charts. It not only makes the game go quicker, the encounters become a series of back-and-forths, a punch and counter-punch, if you will. Oneupmanship is determined randomly, but the result is recognized immediately because success or failure can be determined with a quick glance of the dice.
So it seems only logical — and fair — that the defender also gets the same chance to roll the dice.
This variant is mentioned in the DMG. Basically, the defense roll is 1d20 + armor bonus + shield bonus + natural armor + Dex modifier = Armor Class. (The defense roll replaces that static 10 on the Armor Class chart. Because of this, however, a roll of a natural 1 is not an automatic failure and a natural 20 is not an automatic success, rather just a number added to the Armor Class matrix). This roll can be made every round, or it can be once for each attack being deflected or dodged.
(The rules suggest that making a defense roll once per round is preferable at higher levels, when there are multiple attacks per round, simply as a means to speed things up.)
But the key thing is having the defender be involved in combat, give them a chance in determining their fate. Instead of standing there and presenting a static target, it is presumed the character is doing things to avoid or deflect the blows, and these actions are simulated by the d20 defense roll.
And because the defense roll should be made simultaneously with the attack roll, no table time should be lost, which is an important consideration.
The best thing is, though, it behooves every player to remain focused on the game, especially tactical combat.
Besides, the fun part of D&D has always been rolling the dice. Why shouldn’t players be given more opportunities to roll the dice? The more dice rolling, the better, I say.
The 3d6 variant
Some might say that the 1-to-20 range of a d20 roll is too extreme for a defender’s opposed roll. And it’s a good argument. The attacker should have a broader range of success and failure than the defender, mainly because the attacker has initiative, while the defender must be reactive.
A shorter defense roll range also simulates the reliability of the defender’s armor and not completely negate any bonus gained by having a high Dexterity.
To answer this, I would suggest the defender’s roll be a 3d6 rather than a d20. This gives the defender a shorter range (3 to 18), but because the results in the middle of that range now fall on a bell curve rather than a straight 5 percent chance for any given result, it is somewhat more predictable without being static.
The 3d6 variant is a good compromise for the DM to present to players if the initial suggestion of the defensive roll variant is met with resistance.
Advantage of defensive roll
So, what do you think? Are there advantages and disadvantages with this variant? How will well-armored or highly dexterous characters react to this chance? And what about high-level fighters, who were once pretty sure their primary attacks could hit?
What do you think about this approach?