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.
Black cleaver or frozen mallet.
Depending on wether you want to do huge dammage with the black cleaver, or still do huge damage and have some hp with frozen mallet,it also depends on wether you need slow in your team, and alike, but i recomend frozenmallet, else you die really quickly in battle espesially in team fights, but if you stay behind it works great with black cleaver too.
Sry if i misspell.