The Harsh Possessor is the second boss ghost of Luigi's Mansion: Dark Moon. It is fought as a flight of stairs atop the Tree House in the Haunted Towers. The Harsh Possessor is most notable for being the easiest boss in the game. He is the first possessor to be seen in their own stage before the battle (when Luigi starts making his way to the top of the stairs).
The Harsh Possessor is a tall, white ghost with two horns atop his head. Where the ghost's heart should be lies the third Dark Moon piece.
The battle comes from out of nowhere. As Luigi is climbing a small staircase to a treehouse atop a large tree, the staircase suddenly comes to life and beings attacking Luigi. The staircase itself has two floating antennae, two glowing blue fireballs for eyes, and a set of sharp teeth. Its shape and behavior is remniscent of the piano from Super Mario 64.
Like all Possessors, the Harsh Possessor has infinite health. However, it can still be sucked up.
The first phase of the battle is quite simple. The staircase will simply jump around trying to snap up Luigi. Then after a few jumps, the staircase will leap up high and dive bomb where Luigi is standing. Luigi must move out of the way and watch the staircase crash into the ground and stun itself. A cord appears and Luigi must yank the cord with the Poltergust 5000 in order to force out the ghost. The Harsh Possessor will charge Luigi not once, but two times. After that, Luigi has to suck up the ghost's first layer. The Harsh Possessor will then jump back into the stairs.
The second phase is very similar to the first. The only difference is now the stairs will shoot fireballs at Luigi in addition to jumping and biting. The same technique used as before will be used to suck up the Possessor's second layer.
The third phase is exactly the same as before. The same technique applies.