First off, this build is recommended for those who have mastered Twisted Fates abilities such as timing your Stacked Deck, your Pick A Card, proper placement of your wild cards,and using your ultimate to it's ridiculous ganking potential. Basically, if you have never played Twisted Fate before, this guide may not be for you.

I pick magic penetration runes for obvious reasons, your bonus damage for all spells is magic damage. The dodge runes you may not understand completely, but I will explain why this is amazing. The dodge chance pertains very well into the defensive mastery build by making "Nimbleness" trigger a lot of the time, which can save you from ganks very frequently. Mid solo is your aim, and that is usually a lane that gets ganked early by a jungling Udyr or Shaco etc.. Also, you will get targeted a lot, well, because you are TF and everyone hates his guts ^_^

My mastery build gives you a very helpful bonus to your magic damage output while giving you the best possible defenses you could want playing a very quishy champion.

This item build concentrates solely on ability power, making you a huge threat in team battles with your wild cards doing nearly 800 or more to at least three targets (if used properly). Taking an early soulstealer along with boots will usually result in 3 or 4 charges before level 9 (with the help of your ultimate). Once you get your sheen, and a few soul engorgement charges, you can start ulting around the map to make the enemy carries feel like morons. Basically you find that one dumb Miss Fortune or Ashe trying to push your top tower, select gold card, ult into the bushes behind them and annihilate them with your stun, 350+ damage nuke, and your constant spam of stacked deck. Pretty soon you can afford Rylai's Scepter which is amazing because your enemies think they have escaped your gold card. Oh wait, your wild card suddenly slows them 35 percent! Now you can catch up and destroy them, crushing their morale. WHERE YOU GOIN!?
Next, finish up your lich bane and buy a deathcap if you haven't already won, or throw on a Banshees Veil if the other team has cordcore initiation such as blitzcrank or amumu etc..

This skill sequence allows for the use of gold card, which deals decent bonus damage but has that amazing 1 second stun. Next, it utilizes your wild cards early by getting ability power to constantly harass your opponent at mid lane. Maxing all levels of stacked deck after wild cards is always helpful because it's an amazing passive skill that can dish out an insane magic damage bonus. Finishing up with pick a card only increases your stun length and bonus damage, therefore increasing your potential to dominate. But I prefer to max this one late because the 1 second stun is more than efficient in the first stages of the game.

I pick Exhaust and Cleanse because they both benefit twisted fate greatly. Exhaust can almost guarantee an early kill or first blood at mid lane because, with your mastery build, reduces their magic resistance and opens up for some great damage output at a low level. Cleanse you may disagree on. But I find it amazing, especially against premade teams or in ranked games. Usually when the other team sees twisted fate they tend to scream "AHHH" and attempt to bombard you with as much Crowd Control as possible. A simple click of a button can save you from so many ganks and can save your life in teamfights late game. It also has a short cooldown which means it can somewhat be ready for every gank attempt. If you strongly disagree with Cleanse, get ghost or flash instead for more escaping and chasing potential.

Twisted Fate is a very versatile champion which can assume the role of a ranged DPS carry or a hardcore magic damage cannon. I prefer the my AP build because with all of your items and spells, you're able to push out thousands of damage in seconds while still being able to avoid crowd control. The item build results with nearly 3000 health at level 18 (if not more) and up to about 500 Ability Power, giving you health almost to that of some tanks, and you'll be pumping out magic damage superior to many AP-Based champions like Kassadin, Karthus, etc..
With your summoner abilities and items, chasing down every hero besides that of a Master Yi (with ultimate) is no sweat.
Enjoy.

-ThyRapier