Bannik is the Bathhouse Spirit in Slavic mythology.
Bathhouses resembled saunas that had an inner steaming room and an outer changing room. A place where women gave childbirth and practiced divinations, the bathhouse was strongly endowed with vital forces.
The third firing (or fourth, depending on tradition) was the offering to the Bannik, and no Christianity images were allowed as it might offend the occupants. Bannik had the ability to predict the future.