Ghoulers have various abilities depending on what they posses :
Zombie = Digging.
Whiter Skeletons = Using arrow and bow like normal Skeletons do (which is strange because it's a wither one), but the arrows are put on fire. Also, sword slashes are much more powerful.
Ender Creeper = Shooting purple blasts.
Charged Creeper = Shooting thunder blasts and lightning beams.
Enderman = Teleporting.
Giant = Growing giant.
Witch = Transforming you into a Pig.
Spook = Spook Hammer.
Slenderman = Behaving like a normal one, but faster.
other Ghoulers = Cloning himself
Player = Going to evil or neutral entities and have them attack you.
Blocks = Charge at you.
Water = Flood the area.
Mummies = Behaving like a normal one, but stronger.
Vampires = Biting.
Burglars = Breaking into houses and stealing items.
Ghoulers cannot posses Pigmen, Villagers, Zombie Villagers, Zombie Pigmen, Pigs, Sheep, Wolves and normal Skeletons or Creepers at all. Instead, they will clone them.
Here are some important lessons you need to know before trying to liquidate them .
Don't throw victory already when you defeat a possesed entitie ! He will just leave the corpse and look for another monsters, sometimes he will even try to posses you !
Don't try to sneak him up from behind. It's useless, he hears EVERYTHING and will soon turn around and posses you ! That is, way going to others :
Most times, he will clone other entities to make it harder for you to kill them all.
But there's also a chance of 44 on 900 (42%) that he :
Will either be neutral against you while forcing on the entitie .
OR he will posses it.
Don't throw victory when it's day again. He will NOT burn and die. He will go underground and search for a dungeon, mine or building and wait there until it's night again, and will leave to search for you forever until defeated.
It's 33% chance he will hide in the village if there's one.
It's 11% chance he will hide in YOUR house.
To realy defeat it forgood, throw torches at him. His sheets will burn and voilà !
Spooks are similar to Ghoulers, but have a hammer with them, called the Spook Hammer, with which they can break bricks and glass, allowing entities to gain on and enter the house. He can also try to slam YOU with it, or even call monsters, lure them to you or even trick them into attacking you. Like Ghoulers, they can only be defeated with torches, and they can also hide to avoid sunlight.