King of Tokyo: Halloween, which is subtitled "Collector Pack 1", includes two new monsters for use with the King of Tokyo base game: Pumpkin Jack and Boogey Woogey. What's more, each monster comes with its own set of eight Evolution cards – first introduced in King of Tokyo: Power Up! – so that each monster can mutate into an even more nightmarish version of itself!

King of Tokyo: Halloween also includes six orange-and-black engraved dice (to fit the Halloween theme, of course) and twelve new Power cards to be shuffled into the deck. These cards are all Costumes, a new type of card that provides a powerful effect, but which can be stolen by any monster that rolls three claws and rips the costume off of you.