Is bruiser Fizz still viable?

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I used to play him like that a lot but his ult doesn't amplify physical damage anymore

He can be but he's no longer really strong. It's more a niche pick now that's only for those people who actually know how to do it properly.

Most of his damage even from autoattacks is Magic damage anyways. You dont get an insane Powerspike with sheen tho. If you dont care about that/run Rageblade or Nahsors instead of Trinity Force its basically still the same. Really effective against Tanks still, but not LCS-worthy if thats what you mean

Maybe if you do jungle and get sated.

For lane I think RoA + Nashor's using fervor is superior.

You probably could play AP Bruiser / / or tank items. But the old AD bruiser really isn't going to work so well anymore.