The party called down Vorn to stop this queen and her invading army, but once she was trapped they backflipped and made her the ruler of Vornheim. At that point, zombies were invading, the city was ravaged, and they decided the entire universe was irretrievably fucked. The only solution was to go back in time.
All of the world's problems were caused by the party themselves. To fix the world's problems, all they had to do was kill their very first quest-giver. If old man Crithens hadn't told them about that secret treasure, they wouldn't have become adventurers, and they wouldn't have gone on to ravage the world. Old Man Crithens was the lynchpin of all the world's woes.
With help from their Benefactors, they managed to go back and kill Crithens easily. The betaverse party stayed peacefully in their peasant village. A new timeline - the Betaverse - was split off. Everything was fine. No zombies, no invading elves, no ravaged Vornheim. There was just one fatal flaw: They were still alive.