World of Van Helsing: Deathtrap

Simply load up the level XII. - Wounded Crag. Make sure you choose Tier 1 on Hard difficulty for this achievement. Doing so enables a quest to "kill all neutral monsters before the last wave ends." I recommend doing this right away, after you set up your traps. Neutral monsters appear on both the mini-map and full map as small clusters of horned monster heads and can only be engaged once the wave has started.

You will have to use teleporters on this map to reach the 3 distinct groups of neutral monsters. Defeating each group awards a separate Silver Chest Key. Collect all 3 of these keys and you will see that the quest has now been marked complete. Proceed with the level as normal.

Once finished, 4 chests will open around you and you will be rewarded with massive heaps of gold. I gained about 130,000 gold on average each time I did this. Depending on your progression through the game, it should take you 3-4 times of repeating this process before you net the achievement.

NOTE: Several people have reported this achievement has a tendency to get "stuck" after 95%+ completed. For me it popped right away. For others it will pop eventually. Try going to Game Hub from Xbox and viewing the achievement from there if it is not unlocking right away. This has worked for me a few times in the past for various achievements.