This item is acquired in-game. See its sources below.
A Rare Miscellaneous, item level 1, binds when picked up.
First seen in build 12.0.7.68887 (Midnight (patch 12.0.7)).
Blizzard numbers items as they are created, so the named items next to ID 264303 (264298 to 264308) were usually added in the same batch as Willie: the same quest line, zone, vendor or reward set.
Nightbreaker's Vambraces ID 264298 · Armor - Plate · item level 100
Viral Coagulation Belt ID 264299 · Armor - Leather · item level 100
Viral Coagulation Sash ID 264300 · Armor - Cloth · item level 100
Viral Coagulation Girdle ID 264301 · Armor - Mail · item level 100
Viral Coagulation Cinch ID 264302 · Armor - Plate · item level 100
Robes of Darkened Deceit ID 264304 · Armor - Cloth · item level 100
Vest of Darkened Deceit ID 264305 · Armor - Leather · item level 100
Mail of Darkened Deceit ID 264306 · Armor - Mail · item level 100
Breastplate of Darkened Deceit ID 264307 · Armor - Plate · item level 100
Mask of Awakened Shadows ID 264308 · Armor - Cloth · item level 100The raw ItemSparse values for item 264303 in the current client build.
Read from the World of Warcraft client build files: Item, ItemSparse, Lock, Holidays, AreaTable and CollectableSourceVendor.
TheWoWDB