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.
In the beginning, ofc, start with doran, pot, and trinket.
Then : why the RapidFire Canon and no Runnan ?
Well, this simple fact : wath's the point of hitting multiples targets if you can't kill them ? Useless. + you have a badass ult that will do the job.
That's why i choose Rapidfire Canon. With the passive, move speed, and critics it's really efficient.
Then, the classic critics+damage : IE.
And Stattik to add a huge dose of attack speed, critic, and a really cool passiv with ult and RFC.
You need Lifesteal, i choose BT, but if you are against tank : you can also take BRK.
In last item one of the two Last whispers, depending on your fav : but against healers (fck you Soraka): mortal reminder, and against tanks the Dominik.
I guess that's it, don't forget to Q anywhere, it's always cool and you can assassinate numbers of enemies (especially junglers), and DO NOT SHOW YOURSELF too soon on teamfight !
GL HF :)