how to indirectly nerf Kassadin, since riot don't want to really nerf him

For some reason riot do not want to nerf Kassadin directly, other then removing some armor from him but the things is that as longs Fleet is being used on him, its not going to do a lot. They need to remove the ap ratio from fleet because that is the thing that makes Kassadin so strong + He is the only ap champion that builds the item, ap tank jungler just go Aftershock. I am well aware of kassadin high ap ratios and low ult cd, its not fine, its not ok, but the thing is, if you can shut him down in the early game, you have a way better chance of him not scaling into a beast but as longs as fleet is being built on him, he will have a way easier laning phase , from the heals