Yeah, I kinda did the same thing, Mr. Friday. Basically when we were told the armor equation was Armor / (100 + Armor), it was a simplification. Its actually (through testing) Armor / (100 + |Armor|).

If you aren't familiar with the |#| it means the absolute value of. Basically if it is a negative number use the positive value of it instead.

So:

100 Armor = .5

50 Armor = .33

0 Armor = 0

-50 = -.33

-100 = -.5

Basically At best you can reduce the damage you take as you reach infinite positive armor by 100%, or you can increase the damage you take as you reach infinite negative armor by 100%.

At best (+ armor), you take infinite times less damage, but at worst (- armor) you only take double damage.

Which is a shame, because going from 100 armor to zero, you are increasing the damage you take by 100% (50% reduction to taking full damage, so a 100% increase in damage). While going from zero to -100 you are increasing the damage you take by only 50% (going from 100% damage taken to 150% damage taken).

Its a shame because they wanted every 1 armor to be ~1% decrease in damage taken (and by the same token every 1 point of armor reduction/penetration increasing your damage done by 1%) When with this implementation, its much less effective putting someone into negative armor then it is just reducing them from a high positive number.