Totems of Undying were originally made to help cure diseases. The Alchemists who made them were very proud of their work and handed some out as samples to the local Medical Units to use.
Everything seemed to go well for awhile. The Totems seemed to give people a second chance at life, cure everything from pneumonia to deadly arrow wounds. They were then procured by the militias to use in battle, against others and to protect their towns from the aggressive creatures of the night.
It became apparent after awhile though, that prolonged use of the Totems had.. strange effects on people. Their skin would get pale and clammy looking, and any magic they used would be tinged with what looked like shadows.
When the Alchemists were confronted about these side effects it was found that the totems were made using using the last life energy harvested from things, from random people who wouldn't be "missed" to the human-esque "Zombies" that roam at night.
The Alchemists were to be held for trial for using souls like this. The guards came to apprehend them and instead died to their hands, each member of the Guild holding a Totem in their left hand while wielding the shadow magic. Summoning jaws coming up from below, along with small deformed looking Fae.
The Alchemists were banished, and Totems banned from being used again.
You can see These Alchemists and their protegee working with the Pillagers now, renaming themselves "Evokers" and seeming to be masters of using this Shadow Essence that their Totems created.