Three Kingdoms of Superpowers: Lu Bu, Shadow Lord, Rules the World

I transmigrate as Lü Bu into a modern Three Kingdoms world and awaken an F-rank superpower as a strongman. The whole school laughs at me. “Hahaha! Lü Bu, the mightiest warrior of the Three Kingdoms, and this is all you’ve got?” I say nothing, but unexpectedly bind myself to the Shadow Monarch System: every enemy I kill can be summoned permanently, without losing any of their strength! When my shadow army blankets the heavens and earth, my former enemies are terrified.