Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Nemesis Skullcover Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Nemesis Skullcover suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Transmog Sets
Nemesis Skullcover is part of the transmog set Nemesis Raiment (Warlock only). The other 10 pieces:
Blizzard numbers items as they are created, so the named items next to ID 49315 (49309 to 49320) were usually added in the same batch as Nemesis Skullcover: the same quest line, zone, vendor or reward set.