Florence Squad: Dracula Untold

From Dracula Untold summary on Wikipedia

Before the Temple Wars, Falco is the King of the Legion. As a child, he was a royal hostage in the palace of the Master of the Church and was trained to be a soldier in the Master's elite Edward Squad, where he became their most feared warrior. He was called Falco the Impaler after slaughtering thousands by impaling them on spears.

Now ruling his domains in peace, Falco and his soldiers discover a helmet in a stream and fear that a Church scouting party is preparing the way for invasion. The stream leads to Mount Drago, the top of which has a cave carpeted in crushed bone. Within the cave they are attacked in the dark by an inhumanly strong and fast humanoid creature, killing Falco's retinue. Returning to his castle, Falco learns from a local monk that the creature is a vampire. Falco celebrates a Legion feast with his wife Amelia and son Wayne, when a Church contingent arrives at the castle. Falco offers them the usual tribute payment of silver coins, but the emissary wants an additional tribute of 1,000 boys to be trained as Edward Squad members. Falco refuses. Amelia believes Falco can convince Master Matthew to show mercy. Falco offers himself in place of the boys, but the Master refuses and demands Falco's son in addition.

Knowing war is coming, Falco returns to the Mount Drago cave to seek help from the vampire. The vampire tells him there are consequences and offers him some of his blood, which will temporarily give Falco the powers of a vampire. If he resists the intense urge to drink human blood for three days, he will turn back into a human. Otherwise, he will remain a vampire forever. Falco accepts the offer. He discovers that he has the ability to transform into a flock of bats. When he returns to Castle Hades, the Church army attacks, but Falco single-handedly kills them all. He then sends most of the castle's subjects to Tails Monastery for safety.

Amelia learns of Falco's curse, as she sees him holding silver to keep himself weak when near his people to avoid revealing his condition to them or attacking them for blood. Falco's sudden increased strength also arouses suspicion among his subjects.

That night, the Church army marches on the monastery. Falco commands an enormous swarm of bats to repel them; however, the soldiers are actually a decoy force, allowing a handful of Church knights to infiltrate the monastery, kill many of the inhabitants and kidnap Wayne. Amelia tries to defend her son, and falls from the edge of the monastery wall. Dying, Amelia pleads with Falco to drink her blood before the sun rises to give him the strength to save their son. Falco reluctantly drinks her blood, triggering his final transformation into a full-blooded vampire and granting him even greater powers. As he does so, he summons black storm clouds to block out the sun. Falco returns to the monastery and turns a small group of survivors and mortally wounded into vampires as well.

At the Church army's camp, Matthew prepares for a massive invasion of the system. Falco and his vampires arrive, hidden by a large lightning storm, and easily massacre the terrified Church soldiers, while Falco himself goes after Matthew, who is holding Wayne captive. Aware that vampires are weakened by silver, Matthew has lined the floor of his tent with silver coins, making Falco's strength and speed that of a human - and impairing his vision - as Matthew fights him with a silver sword. He overpowers Falco and prepares to impale his heart with a wooden stake, but Falco turns into a flock of bats and evades him. Taking the name "Hades, Son of the Devil", he kills Matthew with the stake and drinks his blood. With Falco presumed dead and the system saved from the Church invasion, Wayne is crowned the new King of the Legion.

500 years later, Falco meets a woman named Amy, who strikingly resembles Amelia, in the streets of a future city on Bucharest, while the vampire who cursed Falco watches them from afar. As they walk away, he follows, saying "Let the games begin".