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Drowvoir will stand by its Trainer as they sleep, observing their dreams. Should a nightmare take form, it will quickly devour it so that their Trainer will maintain a peaceful slumber.

It apparently does not feel the pull of gravity because it supports itself with psychic power. If your nose becomes itchy while you are sleeping, it's a sure sign that a Drowvoir is standing above your pillow and trying to eat your dream through your nostrils.