Bloodcharm

Sometimes also known as fleshcharms, are the tell-tale sign of a demon worshiper or a witch. These disgusting charms, remain viscous through decades, only drying slightly with age, with no sign of decomposition or aging.
By the church dogma they are to be destroyed on sight by burning. Anyone caught in possession of one, must be investigated. Simply an imitation of a fleshcharm may cause widespread panic in a settlement or a community. And they are more hated than individuals with black mana. Afterall, one only has the stigma because of the other.
The most notable and dangerous feature of fleshcharms is that they accumulate demonic mana. The older the charm, the more powerful and devious it becomes. Additional the person or group to whom it used to belong also increases its power. A small farming society, accidentally unearthing a centuries old fleshcharm, may quickly become the epicenter of demon cult. sprawling the fanatic worshipers throughout the land.

Creation

The due to the desired nature of the fleshcharms, the only way to create them is through the sacrifice of your own flesh, organs and bone. Only willing sacrifice works. These charms beckons to demons through unknown means, and are a sacrilege towards the gods and divine. The act creating one is enough to lose a divine blessing, though this loss is often reimbursed by dark gifts from the demon lords in return.
The first fleshcharm that a cultist creates is often a 'failure', gaining power only years later. This is commonly caused by hesitation and lack of conviction or attempting to reach out to a demon so powerful that they are simply not interested in even providing a speck of attention towards them. Additionally the type of sacrifice is also relevant. Vital parts are more likely to gain the attention of a demon than flesh cut from harmless areas.
Demon cultists that have created multiple fleshcharms, appear to be unaffected by lack of vital organs, though it still affects their lives negatively. Past this point, two things will happen. Either they will continue sacrificing until nothing remains, becoming a dangerous embodiment of a fleshcharm themselves. Or they will be gifted by demons, granting them new skin and flesh to replace the lost one. Usually these replacements are a horrid transfiguration that make mockery to life. However, higher ranking demons bestow flesh to their followers that may even correct previous defects and scars, making them physically even more attractive than before becoming a cultist.
After receiving gifts, for most cultists the creation the fleshcharms does not stop and rather becomes an addiction, each become more grotesque than the other. As the cultists replace their original and changed body parts into new ones, they become less and less human, eventually becoming the very things they worship.
People with black mana are more likely to receive a gift from the demons, and often succeed even with their first fleshcharm. They are also more likely in becoming witches or warlocks.

Powers

The power of the flesh charm depends on the one who originally created it. The weaker charms are created by cultists who eventually become embodiments of fleshcharms themselves. While potent on their own, these effigies merely only allow demons to spread their influence and slowly accumulate mana. The weaker charms are used for their quantity rather than quality.
The charms, created by people who have received a gift of flesh in return, are much more potent. Their powers vary wildly, and most of the fleshcharms of this category are very difficult to destroy due to their mana density. The One Church often opts to seal the strongest fleshcharms rather than to destroy them.
There is no theoretical limit to the power of a fleshcharm. Almost all demonic artifacts are sourced from fleshcharms or used fleshcharms in the process of making. The fleshcharms that attracted the attention of demon lords are superior to the rest, with some of them powerful enough to create rifts between worlds to bridge demons over to the world. The worst, may even invoke a demonic incursion, threatening the annihilation of all life.
Most fleshcharms are used by worshipers or witches and warlocks as spellcasting focus. The cultists and worshipers generally use the fleshcharms for different purposes than witches and warlocks. Witches and warlocks are the worst type of black mana users who use whatever source to gain more power. They don't often intentionally attempt to bring the demons over. Meanwhile demon cults and worshipers, often seek to bring the demons over and hope to receive power in return. Sometimes witches and warlocks even hunt demon worshipers themselves in order to steal their fleshcharms.
Through the use of fleshcharms magic casters can surpass the limits of magic that shackle regular magic casting. To fully utilize a fleshcharm's power the caster must be intimate with the process of how they are created and familiar with the effigy itself. This exploitation requires that the caster steals or borrows power from the demon associated with the charm. Using fleshcharm is not for the feeble-minded, those without the proper protection find themselves worshiping demons or worse, trapped in an endless nightmare in a catatonic state. Almost exceptionally only those with black mana may use fleshcharms without immediately losing their sanity and soul in the process.