The Mortuary Assistant sigils, Quarter letting wiki.

Sigils of the covetous demons:
Each of the covetous belong to one of the three house of service in the halls of satan - the houses of sin. A demon's true name is composed of four sigils of bondage. Below are the three houses and all known covetous demons within them.

Quarter letting:
When the church found someone to be guilty of sin beyond the forgiveness of God, the accused could atone for their sins and re-enter the grace of God by undergoing a cleansing of sin known as quarter letting. A priest would bless the holy blood that remained in the sinner before cutting the wrists and allowing the remaining blood of sin (known as Cophris) to flow freely into an urn.

The blood would be drained until the accursed became weak. This weakness was believed to be the body being unburdened from the weight of sin. The amount was believed to be approximately a quarter of the sinner's blood. The Cophris was then burned as the blood was believed to be human and part demonic.

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Tools of expulsion wiki:
An entity must be bound to its original vessel and that vessel destroyed in order to stop the process of possession. Throughout my work i have managed to discover and establish a set of tools to bring about banishment of demonic entities. The occupied body must contain the reagent, the mark must have the correct demonic name, and the mark must be placed on the correct body and burned. Below are all the tools i am aware of and their usage.

The Mortuary Assistant the mark wiki:

The mark is one of two tools used to bind the demon to its chosen vessel. Each slot holds a sigil that represents a part of the demon's name. When all four are placed in the correct configuration, place the completed mark on the vessel believed to have demonic tenancy. The mark will react to the baleful reagent inside, binding the demon to it. Once the demon is bound, burn the body.

Uncovering the demons name:
The evocation can only be completed once the demon has inscribed the four sigils of its name into our world. They are hidden from us until revealed by the burning of letting parchment. Once all four sigils are discovered, the name of the demon will be known and the mark can be built.