The Sixth Factor

Just as the artisans were fervently researching the uncertainty phenomena, their bitter rivals—the alchemists, also arrived, and began attempting to solve the mystery of the Uncertainty Storm using their alchemical arts.
Unlike the artisans, alchemists never shy away from the unknown when pondering problems. They always leave an empty slot in their formulas specifically for that inexplicable yet necessary unknown factor involved in a given reaction. The alchemists refer to this type of unknown variable as a catalyst.
The same catalyst, when mixed with different materials, produces countless subtle variations: sometimes it has a catalyzing effect, sometimes it actually promotes restoration, and sometimes it even fundamentally changes a product's crystallized form. Alchemists never seek to explain the reasons behind this; they believe that the unknown element, the reaction, and the materials used are all part of a greater, holistic process, and this process itself is one of their golden rules: the formula.
Based on the formula they'd discovered in the ruins, the Alchemist Camp team leader quickly came to a conclusion: the failed potion preparations they'd experienced were not due to technique or materials, but rather caused by a completely new factor inserting itself into the reaction. It responded to the catalyst's empty place in a relatively stable manner for the first time. Thus, they temporarily named this echo "Phantom."