Kat needs some nerfs holy shit
kat is what a broken zed would look like wtf. i just played against one after not playing her in months. I was ahead early on, then she hit 6 and boom gg. she had fking boots only and destroyed me. wtf she has no mana, you cant give her low fking cool downs and teleports like fking crazy. this shit is broken as fuck.
or 
or
even an
or
can work (but that's more of a skill matchup but, they're alright once they hit 6) to force her into a defensive item first, or a stunner like
or
try to save the CC until she uses her death lotus .And she can't really team fight if everyone's high hp
can keep everyone alive and healthy, and try not to let her get the resets. Consider taking
and a
later is still good if ur ad, even a
is fine vs her, for ap get a fast
will help if you're that worried. Hope that helps <3