Don�´t agree with the non-inclusion of RoA. You cannot deny the importance of RoA to fiddles: extra AP, HP and Mana. I believe it to be ESSENCIAL to the majority of casters.

Also, Doran�´s items cost have increased to 475, which means you cannot start with a potion AND Doran�´s Ring.

I would reccomend RoA as the 3rd item, then as 4th, Abyssal Specter. Only then one should think of a Void Staff.

Why i say this? Well, flat magic resistance reduction comes first, then % magic resistance reduction. After that, it�´s flat and % magic penetration. Check this: http://leagueoflegends.wikia.com/wiki/Magic_Penetration

As the 5th item, i love using Rylai�´s Scepter. More AP, more HP and adds a slow effect to all your skills.
Imagine bursting out with Crowstorm, slowing everyone in the AoE, and then using Terrify and Drain. I know i get double and triple kills using Crowstorm thanks to this expensive, but very useful item.

(6th is pretty much a situational choice. Rabbadon�´s Deathcap rules ^^)

Also, what is this: "Void staff increases your hit points"=?
Where you thinking of Rylai Scepter or Haunting Guise, perhaps?

Nothing against using ignite, if it works for you, then do it. I prefer using flash (useful escaping ganks, and casting crowstorm out of enemy sight, only to pop in with the ultimate) and teleport (fiddles=one of the slowest champs, using this helps you get back to lane quicker).

In the skills description, you do a good job when noting that fiddles is a team player (hell, every champion is or should be, but fiddles in particular is better played when considering the rest of the team.)

Not saying its a bad guide, but you should reconsider these points i have talked about.
Neither -1 or +1.

EDIT: Forgot to mention Runes. As im still under lvl 20, and will not buy any runes unless the Tier 3 ones, i don´t use Runes, so i can´t give feedback on your choice of Runes. Magic Penetration Runes seems a no-brainer, even to my newbie eyes. :)