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.
Who like to kill.
If you are pro you can do Mejai's Soulstealer earlier than shoes, cause you have ghost and flash.
If you are difficult to catch opponent, just wait for most of his creeps to be down and flash to him.
Dont forget that Mejai's Soulstealer loves when you kill someone ;)