Adversary

The Elder Evil, the Hungry Darkness, The Black Throne — these are but a few of the names for the nameless entity that slumbers just beyond our world. For ages, He Who Waits has lurked just over the horizon, perhaps this force was removed from reality by the will of Ro but no mortal nor immortal knows the tale. Perhaps, The Nightwalker dreams of this world, leaking his effluence into the crystal waters of creation. Others say Old Scratch was summoned by the pride of Dheymos or Vanya's desperate efforts to remain among the living. Some say that the despair of Cyrena drew the Lord of Horns to her breast. Whatever the truth, this Unholy Trimunerative was at the heart drawing his attention to our realm.

The Monarch of the Black Alter waits, impatiently for eternity. He waits while his dreaded children seek to summon him from the house beyond the door of night.

Concept
The easiest way to conceptualize The Adversary is as a viral evil; a malicious contagion spreading among man and gods alike. The Adversary exerts no direct will on those who succumb to his taint but they are forever changed - their desires are unwholesome, their hunger unholy, and their methods repugnant.