Read from the World of Warcraft client build files.
How Supreme Runecaster's Crown Compares
Who It Suits
Leather is the armor type Demon Hunter, Druid, Monk and Rogue wear. With Agility or Intellect, Supreme Runecaster's Crown suits Assassination, Outlaw and Subtlety Rogue; Brewmaster, Mistweaver and Windwalker Monk; Balance, Feral, Guardian and Restoration Druid; Havoc, Vengeance and Devourer Demon Hunter.
Transmog Sets
Supreme Runecaster's Crown is part of the transmog set Garb of the Chosen Dead (Rogue, Monk, Druid and Demon Hunter only), which the Appearances collection lists in 3 versions. The other 16 pieces:
Blizzard numbers items as they are created, so the named items next to ID 249682 (249677 to 249687) were usually added in the same batch as Supreme Runecaster's Crown: the same quest line, zone, vendor or reward set.