Aciel (called the God Burner) is one of the old gods worshiped by the old religion and especially by the Cult of Aciel, who believe Him to be the old god most likely to wipe out all other gods. It is commonly believed that Aciel has slain several minor and now-forgotten old gods by immolating the gods and all of their followers. Worshipers of other old gods often believe Aciel to be a servant or ally of Zepar or Nestorats.

His worship revolves around fire, and many of His followers believe that He grants visions of the future in the flames. His more fanatical followers often severely burn parts of their body in tribute to Aciel. In the Cult of Aciel, members must survive a gauntlet of fire to be inducted into the cult.

Aciel is commonly depicted as a phoenix or as a red dragon.