As a Kassadin main I find it extremely hard to keep up with this meta's champions.
For example, having a Vlad, Hecarim or a Vi against you basically tells you that you're gonna be useless until you get your 4th item. And the enemy team's adc will still deal more damage with one AA than your full combo. Not I'm not tilted or anything, in fact I find this as a good chance to start maining other champions and expand my pool. But this still needs to be resolved. Nevertheless my damage late game is pretty huge but getting to that point is nearly impossible when you have such a hard CC, hard damaging and extremely tanky champions atm. Not to mention the "Tank-Mage-1 shot Possibly highly mobile" thing. I think Riot needs to balance this area.