Any contact between a Potions Master and a private individual seeking the services of an assassin is called a Black Book. They are kept recorded and documented. All potion masters are required to submit records of their active Black Books to the International Council's Intelligence Committee without notice.
To document the contract between a potion master and his client, stating the client's desire to kill or incapacitate a third party.
Documentation is subject to recall by the IC Intelligence Committee at any time, without notice. Otherwise, it is considered private information and kept secure.
A properly documented Black Book absolves the potions master of responsibility for the death of the named third party.
Vellum / Skin