Talk:Katarina/@comment-75.132.149.126-20110929222145/@comment-3546228-20111001045035

Because most AD items give crit, attack speed and on hit effects, which are stats Katarina cannot use. AP on the other hand has items like Deathcap, Rylai's and Abyssal Scepter which are just what Katarina needs. Survivability, her spells slow and lots of damage.