This image shows the transformation of a possession into my fanfic by a miasma type of evil spirits, who then begins to take possession of the pony, leaving him aggressive, bloodthirsty, malignant, causing him to commit atrocities such as killing his own wife and children , But they can only possess ponies that possess negative thoughts when they are in the environment ie if you have any negative thoughts like: anger, hatred, sadness and fear mainly, you would be releasing negative miasma so a miasma spirit might possess you . So the secret is to think good and happy things when you are facing these creatures.