In order to get this achievement, you'll need to purchase every single costume from the vendor. In order, you'll need to collect every single crow skull. This may seem tricky, but it's important to look back at every door way to see if a skull is behind you. Everytime you climb a tower, make sure to look at the top for a skull. Everytime you cross a bridge, make sure there is a platform below for a skull. You should naturally get these for most of the levels, but a few you really need look at every spot of the map.
Here's a video that shows all of the crow skull locations as well as the gramophones.
All credit goes to Onslaught o