I Became the Psycho Villain's Ray of Light

She transmigrated into a doomed cultivation novel with one mission: save the villain before he destroys everything. Qi Yan—a half-demon prince locked in darkness, tortured and forgotten while his brother basks in glory—is destined to become a world-ending psychopath. When Yun Zhao descends into his sunless dungeon, she's his first glimpse of light in years. But can one girl's warmth melt a heart forged in betrayal and demonic power? As she races against fate to prevent his descent into madness, she discovers the line between salvation and damnation is thinner than she ever imagined.