Why is leblanc this busted

Alright so question. How can a leblanc that's 1/0 with just ludens and mobies literally do 1400 damage to a 6/0/3 Kai'sa with Stormrazor, zerker greaves, guinsoos in literally less than a full second? She had less CS than almost everyone in game, she had no kills, no items but for some reason anyone besides Sion she was effectively able to 2 hit. There is NO counterplay. Literally she looks at you, you fucking die. When her Q is a click on ability and her jump is an AOE thats almost immediate, there is no fucking counterplay besides burning flash but then OH WAIT! She can use her ult to nuke you. What that, build MR? Oh Yeah, let me sell the few items I have to build some MR and totally ruin my build just to what, live for 3 more seconds? Im gonna trade all of my damage for 3 extra seconds? I wouldn't mind if she was maybe like 16/0 but this has been maybe my third game in a row where I'm fighting a leblanc and she just fucking nukes me even when she isn't fed. Me and my friends arent touching this game until I see a nerf or just her getting removed. This has been way too much. There is zero counterplay. You Literally would have to go all MR tanks. I know its a meme at this point but seriously riot. Fix. Your. Game.