Really IC/BW gets best if you can do something absurd like full power attack all the time with a weapon that has a wide critical range, because then you don't need to hit AC to hit; you just need to threaten and voila, autoconfirm!
Increased Threat Range
Sometimes your threat range is greater than 20. That is, you can score a threat on a lower number. In such cases, a roll of lower than 20 is not an automatic hit. Any attack roll that doesn’t result in a hit is not a threat.
