Please Use Mana Sparingly

The boundary boat was shattered, Shen Yan, the cultivator of the God Transformation Formation, fell into the earth, and his cultivation level dropped to the third level of Qi Refining. There is no spiritual energy here, so a pool of mana in the Dantian requires less energy. In order to survive, he had no choice but to hide his identity, repair things for food, use waste materials to build formations, and look for cultivation resources from strange fragments. When the method of cultivating immortals hits the modern city, how can a deity with limited magic power survive?