Hocus Pocus Hall is one of my favorite rides in Chessington World of Adventures. In short it is a 4D walkthrough experience built inside Burnt Stub Mansion situated in the center of the park.
The story is you are going on a tour of Burnt Stub Mansion, home of a wacky wizard. However the wizard's mansion has been taken over by Goblins doing all sorts of naughty stuff. I won't say what there all doing inside, but there are things that will make you jump and other's you'll just watch and go eww. To finish the ride you also exit through a mirror maze just to add another bit of fun to the end of the ride.