They've announced mazes that late before. Nothing unusual, honestly.
I have two guesses, I'm probably really wrong. This is based on the other guests that'll be attending ScareLA that have been announced already.
1 - UCM will be "Tales From the Crypt presents." John Kassir, voice of the Crypt Keeper is there. Just a possibility.
2 - The big hulking facade in Waterworld is actually AHS: Asylum, and the guest will be Pepper, also slated to attend.