Don't get it either.
Even if it was simply a minus percent, instead a percented percent, the defense we're talking is ignore defense.
Omar, this is not a "chance to boost damage" it's a chance to ignore defense ignore, (and I assume it can't ignore past the actual number, unlike crits) so there shouldn't be some reason why you have to get 100% in order to completely remove ignore. 75%-75% is 0% defense ignore (with no negatives this means 0% reduction of 50k high is 50k high, and whatever low). Anything else is absurd, especially since if it's multiplied by the % it's now dependent in the percent itself (which is totally broken), instead of a flat reduction.
75%-5% = 70%
50%-5% = 45%
25%-5% = 20%
5% difference, period.
With the other formula, it's something like this.
30% = ~4%
50% = ~7%
70% = ~10%
Nexon, please explain why you can't do simple math. (monster_reduction - (various armor sums+ skill/other bonuses)) = x% , and x=0 if x<0. Even someone like me can figure out code like this, and I failed the math section of a GRE. This is broken as all hell, because at a certain point, you run into the Law of Diminishing Returns.