Well this is the build that i have been doing quite well with, you need to be able to be good at doing hit and runs and moving across the map for constant ganks. If played well this build works like a charm, I can fairly consistently get about a 2 to 1 kill death ratio with this build.
Note on Item build: yes you buy the items in that order, but you sell the picks as the time goes on to make room for Zonyas -> Scepter -> Staff
Ignite is a great way to get early game kills and finishing later game, flash can be used quite effectively to escape in combination with shadow walk as well as a great offensive ability as well. you can get countless kills by popping your ult flashing into the tower with their hero teleporting out- kill him and get out.
Runes are for damage increase and survivability although I am currently considering swapping out my hp per 5 for AP per level.
If you have questions or constructive criticism feel free to post.