Would you be more scared of a guy dressed in a velociraptor suit or a ghost girl that appears out of nowhere in a broken elevator? Do you know of a more traumatic prank than any of these?
Japan has just raised the bar on pranks forever. There's putting buckets of water above doorstops, filling someone's cubicle with packing peanuts, and now there's making a dude think he's being chased by an actual fucking velociraptor.
Seriously, if your prank doesn't involve the prankee either 1) having a heart attack or 2) wetting themselves in abject fear, then you might as well go straight back to the drawing board.