The game's collection data lists Chain of Shadow as sold by a vendor NPC in Warspear.
Vendor
Zone
Map
Waypoint
Other items it sells
NPC #88569
Warspear
-
-
166
Vendor NPC, zone and position come from the client's collection source tables (CollectableSourceInfo and CollectableSourceVendorSparse); coordinates are the in-game map readout.
Build history
First seen in build 5.5.4.69585 (Mists of Pandaria).
Read from the World of Warcraft client build files (JournalEncounterItem, JournalEncounterCreature, Achievement) and the Blizzard Game Data quest API.
How Chain of Shadow Compares
Who It Suits
Mail is the armor type Evoker, Hunter and Shaman wear. With Agility or Intellect, Chain of Shadow suits Beast Mastery, Marksmanship and Survival Hunter; Elemental, Enhancement and Restoration Shaman; Devastation, Preservation and Augmentation Evoker.
Transmog Sets
Chain of Shadow is part of the transmog set Regalia of the Firebird (Shaman only). The other 16 pieces:
2 other items in the current build are also called Chain of Shadow. Same-name entries are usually a different rank, faction, quest stage or reward track of the same object.
Blizzard numbers items as they are created, so the named items next to ID 87030 (87025 to 87035) were usually added in the same batch as Chain of Shadow: the same quest line, zone, vendor or reward set.