Personally, I think Stupefy, Petrify, and Pacify in the Proficiencies tab are all helpful - not essential, but useful. Mystic Dispersion is amazing for mystic champs and always helpful if you have a good mystic rosterIt's up to you how you play though - I don't use the Ouchies Masteries, for example, but I know how helpful they are, so play how you prefer
what are the best prestige masteries?