Source of the Flow
The Source of the Flow is object and location in The Minish Cap. It is located in the Veil Falls and Link is able to fuse a Gold Kinstone with the object. The required Kinstone is acquired from the Royal Crypt deep within the Royal Valley. Link receives the golden kinstone from King Gustaf.
After fusing Kinstones with the Source of the Flow, Link is able to journey through much of the Veil Falls, eventually leading to the Cloud Tops.