Darkmoon Defender

The Darkmoon Defender achievement is available during the Darkmoon Faire on Darkmoon Island.

Details
This is earned by turning in all 3 Darkmoon battleground artifacts. You must have the Darkmoon Adventurer's Guide in your bags to loot these items. These items can be looted by removing insignias from fallen enemies in battlegrounds.

All of these items can also be bought and sold on the Auction House.