She has complete access to all dps defensive items and dps offensive items. There is no possible way to itemize against her, especially as a tank. This normally wouldn't be a problem if she was exactly like vayne and could actually die (except vayne has perma invis now for some reason had to pump out that legendary skin).
The truth is kaisa can go GA + Zhonyas + Deaths dance + Manamune(which seems to do waaaay too much fuckin dmg on her q ability) and she tends to 1 shot me as a tank in the matter of 0.6 seconds (chogath building full tank with multiple stacks vs kaisa who's going even and has good cs and manamune).
No I'm not low elo, I've been plat and diamond many of times, albeit not on this acc