Read from the World of Warcraft client build files.
How Anomalous Greathelm Compares
Who It Suits
Plate is the armor type Death Knight, Paladin and Warrior wear. With Strength or Intellect, Anomalous Greathelm suits Arms, Fury and Protection Warrior; Holy, Protection and Retribution Paladin; Blood, Frost and Unholy Death Knight.
Transmog Sets
Anomalous Greathelm is part of the transmog set Anomalous Armor (Warrior, Paladin and Death Knight only). The other 12 pieces:
Blizzard numbers items as they are created, so the named items next to ID 207622 (207617 to 207627) were usually added in the same batch as Anomalous Greathelm: the same quest line, zone, vendor or reward set.