likely going to be the “Mesh” of your enemy…if drag off from the Attach to Component (make sure to have context sensitive checked in the top right of this new box) scroll down to the bottom and find your “variable” for the Skeletal Mesh you want…Attach point will be whatever bone you set…likely use the Snap to target for the location type but in some cases not…try it out until you get what you like…
Let me know if you’ve any questions…