With Vulgrim's explanation, Roy finally understood what he meant.
According to Vulgrim's description, this so-called Well of Souls was a place that Heaven used to purify and condense souls. It mixed a large number of ordinary souls into the well water so that it could artificially produce noble souls. After all, it was too little and too slow to obtain noble souls from humans alone.
From this point of view, the transmute function of the Horadric Cube Roy created was not coincidental. High-quality high-class souls could indeed be synthesized, but the Horadric Cube was simply a divine artifact to Heaven in terms of efficiency! It completely skipped the long separation and fusion process and could directly produce the final product.