Skin of Shadow

The Skin of Shadow dropped from the following bosses in Scholomance:
 * The Ravenian
 * Risen Construct
 * Instructor Malicia
 * Risen Bonewarder
 * Lorekeeper Polkelt
 * Lady Illucia Barov

Blacksmithing

 * Persuader

Leatherworking

 * Shifting Cloak

As a quest objective
This item was an objective for the following quests:
 * Breastplate of Bloodthirst (quest)
 * Legplates of the Chromatic Defier (quest)
 * Libram of Focus (quest)