Role in the episode
Shackles Jack and his gang of thugs were inmates at Camp Mugwomp back when it was a prison compound. Knowing that there was no possible chance of escaping alive, Jack resorted to dark magic to ensure that he and his goons would return long after death, and so it was on October 31, 1864, that Jack cast a spell which would allow him and his cellmates to rise from the dead at the next planetary alignment.
At night, when Shackles Jack's journal is left near his gravestone, his ghost emerges from the grave. Shortly after, the rest of his gang emerge from their graves as well. Jack says that the time has come to find a group of living beings for them to possess. The key to doing so lies in the Mugwomp Cup, which the warden from the prison camp used to keep on his desk. The first living beings who won the Cup would be the ones they would possess. Once the trophy was won, Jack and his thugs would take the winners to the abandoned caves over the lake and perform the ritual that would transfer them into their would-be hosts.
After Brad Morton and his campers from Cabin 6 win the Mugwomp cup, the ghosts set their plan in motion. Jack and his goons capture Brad and his campers and chain them to a rock in the abandoned caverns. Jack pulls out a stalk of laurel, which will complete the ritual and transfer the ghostly goons into the Mugwomp Cup. At sunrise, the ghosts will be transferred into their new vessels.
Jake (in dragon form) and his friends arrive on the scene and face off against the ghostly goons. Jake manages to grab the Mugwomp Cup and drops the laurel into the cup, finishing the ritual. The ghosts try to get away, but the vortex from the Cup is too strong. Jack and his thugs are vacuumed into the Cup. Jake then uses his fiery breath to seal the Cup, trapping Jack and his gang inside for all time.