Like all the other Possessors, this ghost appears as a white, horned specter, the only difference being that, unlike all the others, this one has only three horns. No more, no less.
In this mission, after Luigi gets shot to the top of the Belfry, the Possessor will frighten Luigi, and possess the giant clock face. As the clock hands spin around, the numbers will seemingly get possessed one after another. When the battle begins, the number on the clock will be absent, and the clock hands, now seemingly burning, will twitch a bit before swinging around the clock in an attempt to hit Luigi. After stopping at exactly an hour on the clock, the hands will cool, and several ghosts will appear from the hour the small hand landed on. Luigi has one "hour" to defeat the ghosts or enemies. If he does not defeat the enemies when the large hand reaches 12:00, the hands will swing around, and Luigi will have to try that hour again. If he does defeat the enemies in time, the hands will swing around to the next hour, and the process will repeat until Luigi beats every fourth hour. Luigi can move the hands himself to give him more time, or bring him closer to demise. After he does defeat the fourth, eighth, and twelfth hours, the Possessor will appear and Luigi can take one of his three layers off, after the Possessor charges at Luigi four times.
Luigi's Mansion: Dark Moon
Luigi's Mansion 3