By undone you mean like you perform an exorcism and banish the spirit then you want to get it back?
Its a complicated and dangerous ritual that will bring it back and even the wisest and most experianced priests avoid this so I wouldn't advice you to get it back it will try and kill you
Its a complicated and dangerous ritual that will bring it back and even the wisest and most experianced priests avoid this so I wouldn't advice you to get it back it will try and kill you