Forbidden Spoils

The Forbidden Hoard is a zone wide treasure that requires you to kill a few mobs near the chest to open it. It seems to spawn every hour or so and there's no limit to how many times you can open it in a day/week, so you could do this achievement in a single day if you like.

The location of it is marked on your map when it spawns and it stayed lootable for roughly 5 minutes after the first person loots it, so you should have plenty of time to get to it.

There are many spawn locations but I only recorded a few and it appears on the map if it's up anyways so coordinates aren't much help.

If you are farming these for Wow housing, bring alts and open them with each alt. It counts :)

These chests spawn exactly 30 minutes after the previous one was first looted. On the dot.