Phantoms

Phantoms are creatures which reside solely in the Dangai Cave. Taking many forms, and having many abilities, they can live in the cave without food or water, but chose to hunt anyone who trains in the cave, on the rare occasions it happens, perhaps for sport. It's said that they would die if they leave the cave, as they've grown used to the cave's enhanced gravity due to have been born in their, and they aren't very adaptable creatures.