While Franmalth attempts to absorb Natsu and Lucy's souls, Mirajane discovers the secret to the demons' immortality in Hell's Core, right before Seilah unleashes the restraints on her own power to take on Mira.
Don't forget, I also possess 
all of Hades's magical might!
!لا تنسوا أنّني أملك أيضًا كلّ طاقة هاديس السحرية