The tree tiers of mastery benefits were scrapped soon after they were purposed. It is currently simplified to bonus swings of 75-percent damage. Arpen-like effects have been transformed into Colossal Smash where it can be tightly controlled. In Cata we'll be balancing Strength, Crit, and Mastery. We'll get lots of Stamina from gear and healers might appreciate us taking some dodge.