The Blessing of the Voice

The Blessing is an alchemical recipe for a potion able to bestow a specific Change to a member of the Voice. It enables the user to involuntarily alter other's emotions using their voice.
The nameless then concoction was first used by Edmon Kur in 303 BU. Very few private writings from the founder of the Voice remain, even in the organization's vaults. Thus, it is unknown whether Kur came up with the recipe by pure luck, experimentation, or whether he had some idea on how to recreate the legendary queen's Alfhild miraculous voice. The Blessing's recipe is the most sacred of the organization's secrets. Only thirteen people know its entirety. So far, only two ingredients are a half-confirmed topic of gossip between those in the know who don't belong to the Highest Choir.
Kur lived in the east of Dain, and was close to the site where sefia was originally discovered. The properties of the material were not widely known or understood, yet he was able to not only secure a sample, but also to process it into a form usable in alchemy. This suggests some degree of prior knowledge, especially considering what Kur did next. Shortly after demonstrating his power, he and his followers went on a pilgrimage to settle Queenshome in the north of Dain, close to the Clearspring Meadows. The Meadows, currently under control of the Voice, are the only known source of Mehethal flowers. It is unknown what Kur used in his first attempts, as petals of the Mehethal flowers would be extremely hard to obtain on the other side of the continent. It is pure speculation, but an early version of Bloom, a drug using the same plant, or another psychoactive substance might have been used.
The early recipe underwent several changes over the centuries and is still being perfected, as the results are far from perfect. The role of the Blessing is an unknown for all that partake in it, at least at the beginning. Drinking the potion is one of the several steps in the ceremony of advancement to the Middle Choir. It stands out, but the candidates are convinced that it only enhances the effects of the song performed by their elders to bestow the power on them. Unfortunately, only about ten percent of the candidates respond to the Blessing. The cause of that is unknown. Additionally, repeated use can cause some of the negative effects of sefia ingestion, or even the early stages of the Gardener's Tick. The Change caused by the potion is heritable, as evidenced by instances of the Preacher's Voice in Dain infants.
The Voice puts a lot of effort into protecting the recipe. It actively discourages use of sefia as medicine additive and helps tracking illegal Mehethal flower farms. It remains to be seen whether other activities of the Organization are also connected to the Blessing.