Great Qin: Black Technology, Building Heavy Cavalry from the Start

Ying Mu transmigrates to the Qin Dynasty as the Ninth Prince and awakens a God-Tier Life Skills System! He fills the granaries with sweet potatoes, arms the cavalry with stirrups, and wins the First Emperor over with delicious food. While the court officials are still studying the curved-plow, he has already secretly refined an elixir of immortality. How is this merely a life skills system? He's helping the entire Qin Dynasty ascend!