The guide is decent, but I'm not terribly impressed by your overall build choices. To start, there is an error in your masteries. You can't take Meditation without 3 points in Expanded Mind , and you currently only have one. You'll need to move two more points into Expanded Mind to make up the difference; the one in Strength of Spirit seems an obvious choice for one of these.

Moving on to other things, your rune choice is a bit odd. AP on seals is less effective than AP on glyphs, and M Pen on glyphs is less effective than M Pen on marks. You might be better served by switching to the standard AP caster's Greater Glyph of Scaling Ability Power and switching the seals to either some extra MP5 or armor (which you seem to be entirely lacking in this build), especially in the relatively early game.

9/0/21 is an odd choice for an AP carry mid, as you miss some of the better damage masteries, such as Havoc and Archmage . 21/0/9 is much more standard, for the simple reason that it does do more damage. I don't see an explanation as to why you prefer 9/0/21, and you should include one.

On a separate note, I notice that you take Ignite. Because of this, you should move one point from Mental Force to Summoner's Wrath . That way, when Ignite's on cooldown, it'll give you 5 attack damage and 5 AP. Understandably, 5 AP from one mastery point is greater than 1 AP from that same mastery point, and 5 attack damage can never hurt either.

As with Pluckin Penguin, I'm not sure about starting with the Faeri Charm and potions. You can get more MP5 from other items (including Doran's Ring, which also gives HP and AP) to start, and you should be farming well enough that you won't need the GP10 from a Philosopher's Stone. I'd suggest switching to something that either builds into one of your first items (the boots or maybe an Amplifying Tome to build into Rylai's, Morello's, or a Void Staff).

I dislike starting with the Faeri Charm, due to the fact that there is 3 mana regen per 5. I would rather say take boots 2 hp and one mana pot. Then you can dodge a lot more harass, and catch up to your laner to get off a clutch stun. Overall, though good guide. +1