Essence of Undeath
This poison is derived from concentrated rot and decay found in corpses and imbued with necromantic essence. It is capable of shutting down the brain, asphyxiating the lungs, and turning skin that touches it necrotic. It is rumored it can even turn a living creature into a shambling, unholy undead if it is ingested.
This item is owned by Kvothe. It was pilfered from the necromantic chamber of Brother Birch in the crypt below the old church in Bright Harvest. It was identified by Aberforth the Alchemist, though he almost died in the process.