The Form Befitting Death.

The power he stole from the mark of sin is good enough on its own. It may have made some useless changes to him, but it has also elevated his state of existence and made him more powerful.

At the very least, he doesn't need to fear demon gods anymore. Their caustic energy and virulent supreme law are not strong enough to corrode him anymore. If Chaos Energy can't do so to him, then they surely can't. 

He chuckled to himself when he completed the examination of the changes his body had gone through.

"Demon gods are going to make fun of me again."

His form has been reduced to just 10 meters tall. He has also lost all his features. He doesn't have arms or legs anymore. One might mistake him for a ghostly apparition. They would be right, because seeing him is the same as seeing death.