If you haven’t heard, tier sets are going away in Battle for Azeroth. So Antorus (Tier 21) will be the very last tier where we get class set bonuses. It’s also the final tier of the expansion, so that must mean Blizzard is going to give the system a nice send off and give us some truly cool bonuses to enjoy while we wait for BfA, right?
Oh, sweet summer child. No.
Updated Feb 6, 2018: Updated set bonus section for small hotfix buff to T21 4pc. It now reduces the cooldown by 3.0 sec. See the Set Bonus FAQ for discussion on this.