A Stone Spirit from the Start: Taking a Demon Lord as My Grandpa

This probably counts as xuanhuan, though I don’t know how it ended up categorized as xianxia.

Abandoned by my sect, I became the savior of the demonic calamity.

Shi Wan draws out demonic energy to save his master’s wife, only for his sect to brand him the “culprit behind the demonic calamity” and seal him away in the Ashen Realm to fend for himself. At death’s door, he fuses with the core of the Kshatriya Demon God, evolving the System inside him into a forbidden weapon: the Law-Smelting Furnace Engine. It refines demons into energy, replicates laws, and binds Fire Dao companions!

During ten years in the Ashen Realm, he and Yuan Zhuo go from loathing one another to living in symbiosis, feeding on demonic energy and wielding true fire as a shield. When he returns to the mortal world, his master is drinking away his days, his senior brother guards the mountain with an amputated arm, and Guanghan Palace has seized the spirit veins amid the demonic calamity...

If the righteous sects won’t make room for me, then I’ll rewrite the rules with demonic flames!