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.
I play shaco alot and I just happened to through this kit together to make a build that wouldn't have me hanging off late game being no help in teamfights besides finding and taking out slowly target. This build really worked 10 times better than I thought it would and you don't have to give up the damage because he still does plenty!