Locarnum

Location
is the Mystery Merchant you will find in various locations around Val Kaeli.
 * Kanstria
 * on top of Black Mountain near Cyasma Spire entrance
 * Melgatol Portal northernmost platform
 * on a cliff that overlooks the Melgatol Portal (MM discord)
 * down near Agnurok Engine (forum post)
 * Southern Teleport Platform
 * Shroud Outpost in Granarkus
 * Helkir Grotto (global chat)
 * near Queen's Lair Entrance (MM discord)
 * near entrance to Nest of the Shaper area (MM discord)
 * (middle of Granarkus, no details) (MM discord)

Mystery Merchant Shop
's shop information can be found in this list here

Trivia
The only Difference in the all of Arborea's Goblin merchants in the color of their backpack. has a what color Backpack?