Hmm that Arbiter change seems really interesting. Our 4set is making SR less effective due to high RC uptime. With a good castigator-bracers sweep you have 60-70% RC chance. This makes Arbiter a talent to go maybe in Nighthold. Plus this trinket http://www.wowdb.com/items/140806-convergence-of-fates and SI-Legen Shoulder combo we might be able to line Apocalypse-Arbiter-DT windows twice-thrice for 5 minute encounters. This is powerful. Also a mastery prior over haste might be a thing. They are balancing around Nighthold for sure..