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.
Skill build is based around solo-mid. Level 1 snare to get the 2 seconds of snare, maxing out soil for insane farm, and shield for insane survivability.
Item build is pretty self explanitory. I get tear so its snowball effect gets optimal effectiveness then rush RoA after bootsso its fully effective asap. After RoA get Sorc boots, then I finish Arc. staff and then get a Zhonyas as soon as I can. Anything after that is up for debate. If you need survivability, Banshees Veil is a great item. If you want more AP, a Rylais is always good.