User blog comment:DeMi189/Katarina guide - Why? Because I can!/@comment-4945936-20120911025908

I completely agree with this guide, well done Demi189. The only difference is that I trade the AP runes for more magic penetration (decent early game and better for late-game when you have high AP from items) and armor (to better survive the few auto and minion attacks that you will inevitably take).