1) Nunu fucks up Trnydamere hard. If you see Trnd, choose the Yeti. Aniva also makes Trnyd quite sad
2) Yasuo still dies to anything with hard CC. Of the top of my sleep deprived head, that would include the likes of Annie, Malzahar, Cass, Ahri, Heimer, and Anivia just to name a few. My personaly fave there is Malz on the account it's a point a click complete lockdown that your allies can capitalize on.
3) If you're still incapable of fighting them because of the 'OMG, Broken Warlords Mastery', remember Morellos and Executioners calling. Those guys suddenly say goodbye to half their healing and that mastery that's so good suddenlyl goes right out the window.
4) A single day doesn't mean ANYTHING with these huge sweeping changes to the game. We need more then a little under 24 hours to actually be able to get a hold on how things are working, and screaming like a child isn't going to change a thing.
5) It's PRESEASON. Things will NOT stay the way they are, they WILL change as Riot tries to figure out what's too good, what's not good enough, and what needs to be done to make things right. So how about try acting like rational, civilized people and actually put those brains to use for once in trying to beat up your enemies.