Fizz is a fucking monster right now. Not assassin fizz, but that bullshit Fizz top build where you get frozen heart as your first item and still do stupid amounts of damage. Get AS quints and AD marks, start flask and rush FH(vs AD) and SV(vs AP) and you will shit on them even if you're the worst Fizz ever. Once he gets botrk you might as well surrender. 8% current Hp+8% missing hp means he'll always do 8% maxhp damage for every auto AND his ult amplifies both physical and magic damage. It's beyond stupid. If you're ahead you can also get trinity force but you'll do enough damage with only botrk + full tank.
I honestly ban him every single game, he is THAT broken with that stupid off-build. Seen a 0-4 Fizz just completely destroy a fed Zed even after missing ult simply because he had a Frozen heart(and no damage items). And it's almost impossible to itemise against him in lane, as he does fucktons of both physical and magic %hp damage. You can't get HP, MR, or Armour.