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.
Why i choose these spells and items
I think Rumble sould be played as a ap offtank. I take flash because it can save you in alot of situations and ignite for more dps and if ur playing against a healing type of champ u will need the 50% reduce healing