These are the fabled armor drops from Destiny of Velious raid instances. At this time, there are two tiers of raid armor. One set drops from the normal versions of the raid zones, the other drops from the challenge version. The same applies to the sets dropped in x4 raid zones accessed from The Fortress of Drunder but not for the x2 raid instance Citadel of V'uul (as it has no challenge mode). Raid bosses drop items for the class archetype, from which subclass-specific armor pieces are obtained.