Basically this is a 3 v 3 build that me and a buddy have found to be the best build out there. I'm going to write more here when I get some time but try this out and leave lots of feedback thanks.

Pros
+ Amazing heal, making jungling easy
+ Can escape ganks easily
+ Impressive AoE slow
+ More powerful the lower health he is
+ Insane crits
+ Almost never dies late game (If played smart)
+ Amazing mid-late game farmer

Cons
- Squishy early game
- Often targeted in team fights
- Crit-based early game (Not always a bad thing)
- Bad laning phase early game if you dont have ad/crit runes
- VERY susceptible to CC

I personally go all critical chance just for shear ability to get more crits early game. I hold my lane hard early game by just landing one or two crits and low lvls.

Of course its going to be 21-0-9

This was most important i put the exact order to the items and their is good reason. With zeal and boots at lvl 5 or 6 your moving at 400 spd thats as fast as many champs with boots 2. So go BF sword it it most important that you become that carry for your team as quickly as possible. So going bf sword early also gets it out of the way and makes you much scarier while fighting in your ult. Then get crit chance and you can complete Infinity Edge around 13 or earlier in some games. Some games though you don't get IE till 14 but make sure to be farming those jungles thats very important. You can dragon around 9 or 10. If you havnt already killed the dragon do so as soon as you buy BF sword. After IE complete phatom dancer and then boots and at that point your almost unstoppable.

I'll write more later thanks