Hauntii

This can be found in the "Where We Gather" level of the Mushroom Spirit Wood world. In the center of this area is a large stump with a warp point doorway at the front, and on the top of the stump you can see two large ghosts around a black slab that is glittering. Go through the "front door" warp point to enter the Stump Cafe shop, then go up the ramp around the outer edge to head upstairs and get on top of the stump. Possess the glittering slab/table and use left stick to slide it back into the wall to unlock a star and this achievement.