The Great Tang: You Want Me to Be an Immortal Master, but I Actually Use Magic

Ye Nian, carrying a game system, accidentally travels to the Tang Dynasty. Can't make guns or cannons? No worries, how about a meteor shower? Don't know medicine? No problem, purification and resurrection spells are here! Don't talk to me about military tactics—with a berserk buff, my soldiers are humanoid Gundams! The ministers: 'The Immortal Lord blesses the Great Tang, truly the fortune of our dynasty and its people!' Li Shimin: 'Oh dear, Immortal Master, I'm so nervous being the ruler of the world for the first time.'