Found why is kassadin op
Ok, today i played diana mid vs kassadin, and it was frustrating because kassadin R travel distance is much bigger than dianas R range and i couldnt cast second R after he reiftwalked away.
So i checked on lol wiki, and diana R is suppose to have 125 longer range on R, but i still couldnt catch him with dianas ult after his riftwalk.
I dont know what, but something stinks there.