Guan Yin is the Avalokitesvara Bodhisattva of Buddhism, People have become superstitious over Avalokitesvara Bodhisattva. Guan Yin does provide divination and teaches people to the masses,to liberate people, either through words or actions.
HongTaiSin is a supernatural power, after he became an immortal. Hongtaisin is a well-known fairy good cabinet. Whatever they ask of the gods. he left for future generations to sign for divination purposes, are especially efficacious sign, if you believe it, it will become true.