I Guard the Frontier With a Million-Strong Army, and You Call Me a Traitor?

[Regret Arc]+ [Extreme Body Cultivation]+ [Political Intrigue]+ [No Female Lead]+ [Ruthless and Cunning]

From the start, I transmigrate into the body of a cannon-fodder character tasked with building a city wall, but awaken the Killing System.

After slaying tens of thousands of enemies, I attain sainthood through my physical body, command a million troops, and guard the border!