Game of Thrones: The White Flame's Ambition

Reincarnated into the treacherous world of Westeros as Roman Rivers, a bastard adopted by House Whent, he finds himself inheriting the cursed, melted ruins of Harrenhal. But Roman isn't just an ordinary pawn in the Game of Thrones. Gifted with the miraculous "Pale Flame" a draconic magic that grants him monstrous strength and purifying fire, he has the power to cleanse the haunted lands. Knowing the devastating War of the Five Kings is fast approaching, Roman refuses to bleed for the Iron Throne. Instead, he combines his magical abilities with modern Earth knowledge to spark an industrial revolution in the Riverlands. From inventing blast furnaces and cement to forging an elite, disciplined standing army, Roman sets out to transform the continent's most tragic fortress into an impregnable, utopian empire. Let the Lannisters and Starks play their games; the Lord of Harrenhal is building a dynasty of steel. — Description from novelcodex.org