Place 1 cake layer on a cake board or serving dish. Frost the top with chocolate frosting. Stack and repeat with remaining layers. Frost the entire cake with chocolate frosting and lightly scrape to skim coat the outside. Place gummy worms on top of the cake and place a few in the frosting layers between the cake layers. Sprinkle the top of the cake with oreo crumbles and press some crumbles to the sides of the cake. Sprinkle with chocolate rocks. Decorate as desired with additional candies.