These are my personal Katarina builds. I have been playing Katarina since season two. The insane ultimate damage on the AD build is mostly because of Katarinas AD/attack speed ratio. I rly wonder why noone else is playing Katarina like this :D The AP build is if noone on your team pick and AP, I rly like the bone plating + electrocute because you can go in fast get a kill and go out fast. Currently I am Plat but im looking to climb to Diamond in EUW. Give it a try and let me know what you think :)