Hitroll

Hitroll is a statistic that represents how easily you can penetrate an enemies defenses and land a blow.

Mechanics

The simplest description of how hitroll and armor work is that each hitroll cancels out approximately 6 armor on your target. So 15 hitroll is as effective against 90 ac as 25 hitroll would be against 150 ac. There's also a magic constant of 16 which makes it so that 0 hitroll is effective against the default 0 armor. Calculating this gives your base effectiveness against the armor of the target:

   base effectiveness = hitroll - (target armor / 6) + 16

For example, 0 hitroll against 0 armor has a base effectiveness of 0, and 10 hitroll against 100 armor has a base effectiveness of -6. Note that negative numbers are bad and positive numbers are good.

This base effectiveness isn't the real effectiveness yet. For that, we add a random range. because some attacks hit harder than others, and sometimes you get lucky (or unlucky). There is also a small blindness bonus but it is not known.

   real effectiveness = base effectiveness + random(1 to 25)

This real effectiveness value determines how much of your damage is absorbed by the armor for each hit:

   effectiveness less than 2 = no damage to target
   effectiveness 2 to 8 = 1/4 damage to target
   effectiveness 15 to 21 = 3/4 damage to target
   effectiveness greater than 21 = full damage to target

Also, regardless of the real effectiveness, any attack may do 0 to 9% damage, despite any armor.