The Demon King's Excitement
"The Nephilims are abominations of all existence. Creations that not even we in the Demonic Realm dared to bring forth. With this new force of theirs, the Heavenly Realm's influence on the Mortal Realm slowly took root and these half human, half Heavenly Beings became the soldiers of the Heavenly Realm, enacting their will in the world of humans."
Nyx's revelation was certainly a new information to him as he did not know about such existences as the Nephilims. After all, they had not come to be before his demise in his old life.
Truth be told, even though the three Divine Realms had their teeth constantly gnawing at one another, there were advantages to their rivalry and enmity.
One of which, and which is very important, is that they served to check and balance each other.