Fizz's W is a huge problem.
It has ridiculous damage. Take, for example, my recent game where I rushed Hexdrinker versus a Fizz. Him using just his W puts me at half health.
Now, whatever, it wouldn't be so bad if he could do this while building AP Assassin.
But he can do this while building tank, and that in my book is completely ridiculous.
Nerf it.
AS a Fizz main I agree that the base dmg is too high, but there's another problem in reducing it. You will make it so that E is the only ability to max first, and then w for the cdr, this was the case before the rework, w was the last to max because it had low scaling and q second for its reduced cdr and mobility. Now that q is 8s at all ranks there would be no reason to max Q over W or W over E.
That would be the same as reducing Irelias W to 40 or less true dmg with 20-30 starting. She would have 0 reason to max it first or second.
Fizz is in a good spot right now. The upcoming MF/level buffs for all champs and more MR items are gonna a screw ap fizz hard.
