The Gotham Terror entites by itself, no addtional  shenaigans. you can use it in your own just credit:

        Go PLAY THE Official Gotham Terror Project INSTEAD!

                                                                    UPDATE 2 IN THE WORKS!

                                     The Definitive Batman Horror Experience created by your favorite minecraft                                                                                          mob themed youtber, the Krafted Kreeper. 

                    Inspired by the unanswered cries from batman fans alike, Gotham Terror adds the horrifying                                         experience of the Batman's more creature of the Night Aspect from the Criminals perspective. 

                                                                       The Criminal........Being You

                                                                  ITS THE FREAKING BAT!

                        In an effort to fully recreate the infamous attack patterns of the Batman, often found in other games such as the Arkham Series, three custom coded mobs spawn every night to make your playthrough  truly terrifying. 

       The Knight 

                 This entity recreates the scary sight of Batman shadow creeping across the darkness just out of sight. If you don't see him at first.....you will eventually

       Vengeance 

                  Entity two, this entity stalks you at a closer range just out of site, dont worry though your sight is your greatest weapon with this one....until it disappears and reapears behind you...

       Vengeance Ariel

                    The last entity to spawn sulks high above you in the rafters of the tree-line lying in wait. If he doesent bring you up to him, the last thing you may see is the terrifying sight of him gliding toward you