I said that the skill sequence is just a suggestion... On Fizz you can max first all skills and it won't be wrong!

I believe that the hourglass is far less situational than void staff, since it gives you much more AP (and an amazing untargetable active), and a lot of times void staff does only a small amount of magic pen against enemies in the mid lane. Since most AP Carries have no scaling MR, for the majority of the game their MR will probably not exceed 70, which means you get about the same magic pen as if you got the abyssal scepter. So unless you are against a Galio, or some kind of tank or bruiser with high MR, void staff isn't worth it.
Also your urchin strike does the least damage. I max E first for damage, AOE farm, and the crazy CD reduction (which helps getting out of sticky situations). Then I max Q since it gives me CD reduction, and a small damage increase. The main reason I max Q after E is for the CD because then I can attack or proc Lich Bane more often. Q can also be used as an escape or dodge if you overextend.
This is personal preference since I like to build fizz as a heavy nuker, so I appreciate if you took the time to read this.

Nice work, guide is great!

OK guide, but it should be a bit more in-depth.

Thanks :)

Good guide for APC Fizz.

Éste es el orden en el que yo mejoro las habilidades, es el mejor sin duda, y la build es casi la misma, y de las maestrías más de lo mismo, muy buena guía sin duda.

Thank you! I'm still working on it.
EDIT: Added abyssal scepter, mejai's soulstealer, morellonomicon and banshee's veil to situational items.
FInished and published Situational Items section.

Nice guide! IT helped me much

Also think about Abyssal Mask, it's one of my core on Fizz due to it's AP and Mres, plus the FLAT MRES DEDUCTION is a great trade off to Void Staff if the enemy doesn't have very high mres.

-Absolute.0

I will explain when to buy ROA when i'll finish the whole situational items section.