The Death Row Emperor

Orion Drake, a top assassin, travels to ancient times, becomes a death row inmate, and activates the 'Slayer System'. He stages a comeback in the army, eliminating tyrants, but is condemned by the imperial court. He feigns surrender with General Seraphina Ashwood to infiltrate the Northern Hordes. He slays the enemy chieftain, achieving victory. His success incites the emperor's jealousy, leading to his framing. He kills the emperor and seizes the throne, forging an invincible legend.