Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Poisonroot Belt Compares
Who It Suits
Cloth is the armor type Mage, Priest and Warlock wear. With Intellect, Poisonroot Belt suits Discipline, Holy and Shadow Priest; Arcane, Fire and Frost Mage; Affliction, Demonology and Destruction Warlock.
Transmog Sets
Poisonroot Belt is part of the transmog set Vesture of Borrowed Souls (Priest, Mage and Warlock only). The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 134423 (134418 to 134428) were usually added in the same batch as Poisonroot Belt: the same quest line, zone, vendor or reward set.