From the Start, I Fused with the City Core and Turned a Ruined Outpost into an Empire

He transmigrates into the body of a useless border lord, and from the start, a baron is at his gates with an army. He activates an out-of-control altar, and a blood sacrifice summons three hundred bloodthirsty, steel-armored beasts! From then on, things take a wild turn: sacrifices of battlefield remains summon Bloodwing Knights and Calamity Dragons. To command the monsters, he sacrifices “fear,” and never retreats again. The empire's cavalry? Torn to shreds by the steel-armored beasts. A horde of monsters surrounds the city? Perfect, more offerings. Amid blood and fire, a wasteland rises from the ruins. The abyss is merely a tool for him to devour and conquer.