Historically, the best clues about upcoming adventures have been:
- Adventure books. For example, Storm King's Thunder told us that Artus Cimber and the Ring of Winter would feature in a future adventure (which turned out to be Tomb of Annihilation).
- Novels. For example, RA Salvatore's Hero told us that Acecerak was now residing in Chult. Unfortunately, the novel line has been discontinued, so this well has dried up.
- Acquisitions, Inc. games at PAX. Chris Perkins likes to incorporate upcoming adventure themes into his games.
Maybe there will be a clue at the Acquisitions, Inc. game this Saturday.