Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
buy 3 doran's Blade at the start before you start with the boots.
the go straight into the infinity edge after the you can go with a Phantom dancer or frozen mallet but make sure you buy then both that will keep them slow and then you don't have to use your Q spell which will save you mana.
when you buy those items go for a Bloodthirster and then finish it off with your last phantom dancer.