"Happy Hunting Ground" is a phrase that originated from Native American mythology, depicting an afterlife where the spirits of the dead can hunt and live freely. If we were to use synonyms for this phrase, we could go for terms like "Elysian Fields," which refers to the paradise-like afterlife in Greek mythology. Another synonym could be "heavenly abode," which means a place of eternal bliss and happiness. "Promised Land" is also closely related to the concept of a hunting ground as it denotes a land promised by God to those who uphold moral or religious standards. Lastly, "paradise" comes to mind, which indicates a blissful place of tranquility and pleasure.