Having just acquired the Elemental Beta yesterday, I have been reading the beta forums.
I noticed that it seems that Stardock is planning to use a system where attack and defense rolls are a single randomly generated number between 0 and the attack rating, with every number having an equal chance.
I don't really like that system, since it is too random: You would need absolutely ludicrous amounts of defense for a powerful creature to be able to withstand to a horde of lesser ones. Brad proposed the idea of having a minimum roll of Defense/10 for defense, but that seems rather arbitrary to me, since that means a single point of extra defense could be the difference between tough and absolutely invulnerable.
I propose a more bell-shaped distribution for attack/defense rolls, instead of such arbitrary minimum rolls, similar to how master of magic did it. If you have, for example, a single defense roll for every point of defense you have, with each roll having a chance to block a single point of damage/attack, you naturally get that powerful creatures are almost impossible to harm with weak attacks, without making them too strong against normal ones. Since probabilities lower, but never get to zero, large armies of weak troops can still be a threat to a strong unique creature, without them killing it instantly.
If you have an army of a thousand archers, and an even distribution of defense/attack rolls is used, the average damage of a single archer would be very difficult to get below, say .05 per volley. That would be the equivalent of 1 attack versus 9 defense. With a thousand archers, you would still get 50 damage per volley. That means the target is killed very quickly, unless he has thousands of hitpoints/strength.
But if you use the minimum system, a single extra defense point would make it invulnerable, which is too big a change for such a small stat difference. Without a minimum defense roll, to get the damage down to a survivable, say, 5 per volley for this tough monster against the weakest archers imaginable, you would need 99 defense, which is ridiculous.
If you however, use a system of 1 roll per point of attack/defense, with each roll having a 50% chance of adding one to the total, the same monster needs a mere 7 defense in order to reduce the average damage of a single volley to 4. 8 defense, would halve that to 2, 9 halve that to 1. 2 attack versus that same 7 defense would result in 20 damage per volley however, a great improvement. That may be too steep a distribution, since it can quickly make a unit with a lot of defense very tough to harm, but this type of distribution is still, I think, a good idea. A better one than an arbitrary minimum roll I think.