The cause of his parent's death?

"This is for all the humans that died because of you."

Pa! Pa! Pa!

Endless rains of powerful slap rained down on the face of the serpentine devil, causing its necks to twist. Its jaw dropped, and its tongue stuck out of its mouth. With its wagging out of its mouth and injuries all over its face that was as swollen as a baboon's ass, the onlookers thought that the serpentine devil looked like a badly abused street dog! Just the thought of comparing the great terrorist to a dog poked the funny bone in their body and made them laugh unconsciously.

Elliot humiliated it so much that it unconditionally puked out one mouthful of blood after another.

Of course, the more blood the serpentine devil lost, the better Elliot felt. Although he had a smile on his face, his entire being was blazing with anger. If one looks closely at his face, one will undoubtedly notice that swirling in his eyes was immense rage that threatened to destroy the world.