(Actually you would end up crushing your own skull...meh)
Frankenstein let go of Mirby, but not because of her headbutt, but because Bluebeards repeated attempt of pulling out his soul amused him.
Like last time Bluebeard was hit by some strong lightning like energy...thought it wasn't exactly electricity. The ghost let go of Frankenstein's spirit.
"Omnipotens Vox. That's the name of the glyph that not only powers my body, but it also binds my soul to it. In other words I am immortal. My soul cannot be forcefully dragged out of this body and this body cannot be destroyed as long as I am connected to it."
Frankenstein opened his elbow and brought up another grenade. He crushed it in his hand, but instead of exploding the grenade released more poison into the air. Frankenstein looked at Mirby
" This dosis shoul be more than enough. I don't want to damage your body, so this will be the most fitting way. As for you ghastly sword"
The doctor grabbed Hachi and sent more of his Glyph's energy into it. The sword wasn't compatible with that sword of energy and weakened Bluebeard in the process, making him slowly lose control over his sword.
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The moment the Cerberus released it's final breath, the two heroes were mercinlessly attacked by the personal guard of Death - Gaibon and Slogra. The blue dragon attacked Morder by spitting fireballs at him. Slogra tried to impale Dan with his trident