"Nuckalevee. Demons ... of Rot, and Suffering, and Malice. What is known of them comes from first-hand accounts, for even other Demons are loath to speak of them ... and while there are no more than a handful they are consistent; and what they offer speaks to their nature." Ishtar said to start.
"They are monstrous in appearance. Possessed of no skin, their muscles and veins are on display for all: a pulsating necrotic mass of tissue that courses and oozes with thick, black blood. Nor are they strictly speaking humanoid; as their bodies from the waist down are equine ... its legs scrawny and maggot-eaten, it's hooves cracked, and bloody. Their humanoid half is far more grotesque however. A head with two eyes that burn with perpetual hellfire simply hangs from its body, its neck broken and useless. Arms too long for its body, the knuckles a bloody pulp of flesh that drag upon the ground as it walks. To say nothing of the corruption they spread by purely existing, to the point where even the air they 'breathe' and space they inhabit is eaten away at by their miasmic presence." The Oni paused a moment to collect her thoughts on the matter -- for it was a subject she herself had long left alone -- before continuing on in a torrent of words; hurried and hushed.
"As I understand it, there were only ever three, and as I recall only one of them ever possessed a name; for such ultimately means little to their ken. For the first two, not much is known beyond how they eventually came to be beaten down and confined, the First to the lowest level of HIFL: the plane of torture in Otherworld that Parsley is familiar with. The second, ultimately bound in secret by the Galaxy Police ... one of the few good things they have managed in their tenure as universal wards. The third however ... the one we face ? He was known as Baric the Brute and met his end on the Arcosian Homeworld some centuries ago after a protracted siege ... the first of the Nuckalevee to truly die. Or I so I thought.
"Even among the Nuckalevee, Baric was ... unique. The methods he employed to torture and kill eventually becoming more of a grotesque art than anything truly barbarous; and he never tired of it. Even when the others were struck down and contained, Baric continued his lone campaign against the living souls in this Universe. A tally that extends into the billions as I understand it, and at least a hundred worlds now long forgotten. And it did not matter the span. Once Baric set his sights upon a planet, or an inhabited moon, they eventually fell. Each and every soul upon it experiencing as much suffering and pain as their wills could bear before Death came to grant them mercy." Ishtar shrugged, before explaining how she knew.
"I will never forget when I encountered Baric, as much as I might wish it so now that I am no longer the emotionless voyeur I once was. The tenth World Zurvan bore me to witness. A garden-world on the outer rim of known space ... He arrived and no one but I knew. So I watched as he first killed the crops, to sow chaos: miasmic breath and fetid blood eating away at the flora until the world was completely bare of it. Then he waited for the survivors to regroup ... begin to rebuild ... and repeated the process with the livestock. Those who died during these phases were granted a mercy he did not afford the survivors ..." Ishtar trailed off then, shaking her head to dispel the memory before saying simply:
"It took him half a century. He never said a word."
Finished now, at least for the moment, the Oni simply pressed forward.