378- Nature Summer Manual. Testing the Magic Circle- Magic Arsenal
Since, Orochi possesses all the Secondary elements, unlike other cultivators who possess only 1 secondary element; he has to get his hands on cultivation methods related to all the elements.
And from the loot or the storage rings of his enemies, Orochi was able to get the cultivation methods of different elements.
Like the Thunder element cultivation method- Shaking Sky Thunder Manual was obtained from the City Lord of the Border City.
Since Orochi has so many Primary and Secondary elements, why not make use of them to make himself stronger?
But in the storage rings, there was no complete cultivation method related to the 4 elements- Water, Wind, Lightning, and Ice. Hence, he had to place an order at the Golden Cloud Chamber of Commerce.