The thought behind this build is based on a holy AP trinity.
Speed, Heavy Crits and Leech.

Speed in movement, but mostly in your attacks. This is a DPS monster.
With all 2 items based on the BF sword included as well as 2 Phantom dancers you'll have a DPS that will put a smile on your face the whole game.
If you can make a FB, you might even be invincible from Level 7 or 8 on.

Why no magic resist and armor? Simple: You counteract with your leech. Most of the game you have around 20% life steal. Even 70% with your Ult activated. Basically you'll be hitting down someone so fast and furious with so much life steal, you will get out of a 1:1 battle with 100% health.

Once you have your build complete you'll have 100% crit chance with 250% crit damage.
I don't have to tell you what that does to your DPS.

The most critical thing about this build is that if you commit to a fight, you should finish it. Don't run away, just keep on pounding and keep on stunning and throwing your shield up when you can. Endgame, you can hit down anyone who is not a tank in less than 2 seconds, so don't worry about prolonged battles. Even a pro Nasus or Jax will be put down on the spot 1:1 within 4 or 5 seconds.

The way this is built, you need a lot of health. As you don't have items to do that for you, you'll need to last hit and farm critters as much as you can with Enrage enabled. It's not too hard to do, especially mid- to late game, when you squish them with a single hit. Combined with that ridiculous attack speed, you're a 1 man critter splashing army, earning you 3 max HP every single hit. Getting your health over 3K should pose no problem at all.

First you get your boots, try to get FB with your stun and your mate who is preferably a mage or ranged with some form of slow or stun to dominate from the start.

Then when you've got enough to buy speed boots (650) you'll get those.

After that go for damage and lifeleech, bf and Vampyric.
The BF Sword will greatly increase your lifesteal, obviously.

Then finish your BT as soon as possible and fill it right up with some last hits etc.

After that, just go for speed and then more damage, with PD/PD/IE/TRI.

You need to focus on Enrage, to farm health. You want lots of enraged last hits, since you don't use items for your max health.

Start with Cryptic gaze and make it your second most important skill.
You need to use it to stun enemies. Not only do you need it to get close to them, you can also minimize their damage to you or your teammates with it.

You should use your ult any time you can. it can bring a n enemy down fast and you up from the dumps just about as fast :)

It is so fun to play like this. Beating down an enemy in seconds, owning the lanes and especially hit hard and fast. Get ready to be feared... Muhahaha :)