Hello,
Check my new build for Katarina clicking the link below:

http://www.mobafire.com/league-of-legends/build/one-shot-one-kill-katarina-432426

It's a simple build to play and by following it you will carry your team. The item's order to buy it's the one shown in the build from left to right.

Try and rate my build right now.
Best regards, Adrian Plays.