Darkmoon Dungeoneer

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

Details
This is earned by turning in all 5 Darkmoon dungeon artifacts. You must have the Darkmoon Adventurer's Guide in your bags to loot these items.

All of these items can also be bought and sold on the Auction House. Note that A Treatise on Strategy has a much lower drop rate than the others, so it will cost much more.