Black Stone Heart has to be the best fantasy read I've ever had the pleasure of coming across so far. The only ones that come close are The Prince of Nothing series by R. Scott Bakker, The Children of Chaos by John C. Wright, and The Worldbreaker Saga by Kameron Hurley.
"We fight to the end,” said the man. “To the death.” The demon beside him nodded, wizened face sad. Commands were sent out and the demonic host, bound in servitude to the demonologists, had no choice but to obey. That night the Empire fell, and the world sank into a thousand years of darkness."
Black Stone Heart has phenomenal and highly immersive world-building, top-notch characterization, and beautiful, poignant, and macabre prose while at the same time self-reflective due to the POV. It also has a solid magic system that fuses elements of speculative science all interwoven in a highly addictive plotline that keeps you wanting more after every single word uttered by my most beloved anti-hero.
Another thing I found interesting was how the POV kept recovering his memory through dreams and visions of events millennia in the past as he continued recovering his shattered stone heart by walking the Obsidian Path.
I would highly recommend this to readers of GrimDark Fantasy. Here are some beautiful quotes...
"Something was wrong with the old man; he wasn’t quite the right shape. His skull, a little too oblong, his limbs a little too long. He looked stretched. Eyes, too large, oddly oval, glowed violet as he studied me. He blinked wrong, liquid, one eye at a time."
"The demon, in robes of ink, looked like a gaunt old man, bald, bent and near skeletal. “If we break that circle, it might crack the earth to its core. Lava. Ash in the sky for years.”"Creatures called from a hundred different realities stood waiting. Massive beasts, some dwarfing even the Deredi giants, held formation beside winged nightmares from some distant hell. Many, hailing from closer realities looked human, differing only in some small detail. Purple skin, horns, claws, too many or two few fingers. With this army, he had bound the world under a single rule: His. And now, with this army, he would lose the world."
"The wizards might win. Tomorrow, the Empire might be theirs to rule. But it was also theirs to lose. And lose it, they would. Short-sighted, they had no idea just how much the Empire relied upon demons. Demons the wizards had no means of controlling."
"That night I dreamed of a strange hell where demons were immaterial spirits that could be bound to steel and iron. They thirsted for death, fed off the essence of the living as it fled the dying body.
I wanted to summon one, to bind it to a sword. But not just any demon, I wanted their master, the Lord of the entire Hell. He had a name, and it was the End of Sorrows."
"You. Will. Obey!
Fear. Terror.
The water elemental cowered. It remembered me. It remembered how I brought it here, how I bent it to my will.
“Fill the bowl,” I commanded. “If I ask for water, you give it.”
I opened my eyes to find the bowl filled with cool, clear water. I drank until I puked.
Then I drank more.
“Better?” asked Nhil.
“Yes,” I answered, voice still raw.
“Good,” he said. “Because we have another problem.”
I lay back, belly distended. “What’s that?”
“You’re still going to starve to death before long.”
“Oh.” I released a long belch. “Fuck.”
The explicit humor involved was a highly refreshing counterpoint to the deep existential dread, violence, gore, etc., which the plot hinges on; The somewhat slow and fast pacing (towards the ending) was surprisingly helpful.
"Evil. I didn’t like that word. So judgemental. One man’s evil was another’s righteous. The world wasn’t black and white, right and wrong. That was what the wizard’s preached. Evil, like beauty, was in the eye of the beholder. I was not evil. Sure, but was there a way to sacrifice a soul that wasn’t evil? There must be."