Hearing the Call - CoTF Collectibles Achievement
For this achievement you'll need to complete the collectible achievements for four different zones. The Source of the Ethernere (Tainted West Karana), Dead Relics (Dead Hills), Bixie Hive Hodgepodge (Bixie Warfront) and The Darklight Palace (Neriak Fourth Gate). There's four sets of collectibles for each of these zones which means you'll need to complete 12 sets in total.
This is one of two achievements that are required for Master Scavenger of Ethernere. Finishing Master Scavenger of Ethernere will award the player with a 36 slot bag as well as an additional Trophy slot which is a small upgrade but makes a big difference for min/maxers.