-----
Frank's mind seemed to have blacked out.
The pain of crushing his own heart was immense, even as an Undead.
Even Hades knew that this might be a dangerous move.
But why?
Even when he was capable of healing any wound on an Undead through Death Gift, an undead-healing Death Attribute Magic Spell, why would destroying his own Heart be so dangerous?
The pain that he was able to perceive was dulled as an Undead Progenitor.
However, when crushing his own heart, he was bound to feel the pain, nonetheless.
And even more, as he would certainly die if he converted back into the living.
Frank predicted that his heart bursting out would cause enough pain to make him blackout, so he had asked Hades to take over his body.
He knew that Hades was able to do such a thing, after all, both of them were fused as a single soul.
Hades only needed Frank's permission.
Check "The Protagnist's Sister Is Actually the Strongest"!